diff --git a/frontends/nextjs/src/components/ui/organisms/navigation/MenuItemList.tsx b/frontends/nextjs/src/components/ui/organisms/navigation/MenuItemList.tsx
new file mode 100644
index 000000000..29b5007b5
--- /dev/null
+++ b/frontends/nextjs/src/components/ui/organisms/navigation/MenuItemList.tsx
@@ -0,0 +1,109 @@
+'use client'
+
+import { forwardRef, ReactNode, useState } from 'react'
+import {
+  Box,
+  Collapse,
+  List,
+  ListItem,
+  ListItemButton,
+  ListItemIcon,
+  ListItemText,
+} from '@mui/material'
+import ExpandLess from '@mui/icons-material/ExpandLess'
+import ExpandMore from '@mui/icons-material/ExpandMore'
+
+interface SidebarItem {
+  label: string
+  icon?: ReactNode
+  href?: string
+  onClick?: () => void
+  children?: SidebarItem[]
+  badge?: ReactNode
+  disabled?: boolean
+}
+
+interface MenuItemListProps {
+  items: SidebarItem[]
+  dense?: boolean
+}
+
+const MenuItemList = forwardRef<HTMLUListElement, MenuItemListProps>(
+  ({ items, dense = false, ...props }, ref) => {
+    const [openItems, setOpenItems] = useState<Set<string>>(new Set())
+
+    const toggleItem = (label: string) => {
+      setOpenItems(prev => {
+        const next = new Set(prev)
+        if (next.has(label)) {
+          next.delete(label)
+        } else {
+          next.add(label)
+        }
+        return next
+      })
+    }
+
+    const renderItem = (item: SidebarItem, depth: number = 0) => {
+      const hasChildren = item.children && item.children.length > 0
+      const isOpen = openItems.has(item.label)
+
+      return (
+        <Box key={item.label}>
+          <ListItem disablePadding>
+            <ListItemButton
+              onClick={() => {
+                if (hasChildren) {
+                  toggleItem(item.label)
+                } else if (item.onClick) {
+                  item.onClick()
+                }
+              }}
+              disabled={item.disabled}
+              sx={{
+                pl: 2 + depth * 2,
+                minHeight: dense ? 40 : 48,
+              }}
+            >
+              {item.icon && (
+                <ListItemIcon sx={{ minWidth: 36 }}>
+                  {item.icon}
+                </ListItemIcon>
+              )}
+              <ListItemText
+                primary={item.label}
+                primaryTypographyProps={{
+                  variant: dense ? 'body2' : 'body1',
+                  fontWeight: depth === 0 ? 500 : 400,
+                }}
+              />
+              {item.badge && (
+                <Box sx={{ mr: 1 }}>
+                  {item.badge}
+                </Box>
+              )}
+              {hasChildren && (isOpen ? <ExpandLess /> : <ExpandMore />)}
+            </ListItemButton>
+          </ListItem>
+          {hasChildren && (
+            <Collapse in={isOpen} timeout="auto" unmountOnExit>
+              <List component="div" disablePadding dense={dense}>
+                {item.children!.map(child => renderItem(child, depth + 1))}
+              </List>
+            </Collapse>
+          )}
+        </Box>
+      )
+    }
+
+    return (
+      <List ref={ref} dense={dense} {...props}>
+        {items.map(item => renderItem(item))}
+      </List>
+    )
+  }
+)
+MenuItemList.displayName = 'MenuItemList'
+
+export { MenuItemList }
+export type { MenuItemListProps, SidebarItem }
diff --git a/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar.tsx b/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar.tsx
index bd9bdb0a8..760030fbe 100644
--- a/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar.tsx
+++ b/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar.tsx
@@ -1,37 +1,18 @@
-// TODO: Split this file (309 LOC) into smaller organisms (<150 LOC each)
 'use client'
 
-import { forwardRef, ReactNode, useState } from 'react'
+import { forwardRef, ReactNode } from 'react'
 import {
   Box,
   Drawer,
-  List,
-  ListItem,
-  ListItemButton,
-  ListItemIcon,
-  ListItemText,
-  Collapse,
-  Divider,
   IconButton,
-  useTheme,
   useMediaQuery,
-  Typography,
+  useTheme,
 } from '@mui/material'
 import MenuIcon from '@mui/icons-material/Menu'
-import ExpandLess from '@mui/icons-material/ExpandLess'
-import ExpandMore from '@mui/icons-material/ExpandMore'
-import ChevronLeftIcon from '@mui/icons-material/ChevronLeft'
 
-// Types
-interface SidebarItem {
-  label: string
-  icon?: ReactNode
-  href?: string
-  onClick?: () => void
-  children?: SidebarItem[]
-  badge?: ReactNode
-  disabled?: boolean
-}
+import { MenuItemList, type MenuItemListProps, type SidebarItem } from './MenuItemList'
+import { SidebarHeader, type SidebarHeaderProps } from './Sidebar/Header'
+import { SidebarSection, SidebarSeparator } from './Sidebar/NavSections'
 
 interface SidebarProps {
   children?: ReactNode
@@ -42,7 +23,6 @@ interface SidebarProps {
   anchor?: 'left' | 'right'
 }
 
-// Sidebar Root
 const Sidebar = forwardRef<HTMLDivElement, SidebarProps>(
   ({ children, open = true, onClose, width = 280, variant = 'permanent', anchor = 'left', ...props }, ref) => {
     const theme = useTheme()
@@ -76,227 +56,66 @@ const Sidebar = forwardRef<HTMLDivElement, SidebarProps>(
 )
 Sidebar.displayName = 'Sidebar'
 
-// SidebarHeader
-interface SidebarHeaderProps {
-  children?: ReactNode
-  onClose?: () => void
-  showCloseButton?: boolean
-}
-
-const SidebarHeader = forwardRef<HTMLDivElement, SidebarHeaderProps>(
-  ({ children, onClose, showCloseButton = false, ...props }, ref) => {
-    return (
-      <Box
-        ref={ref}
-        sx={{
-          display: 'flex',
-          alignItems: 'center',
-          justifyContent: 'space-between',
-          p: 2,
-          minHeight: 64,
-        }}
-        {...props}
-      >
-        {children}
-        {showCloseButton && onClose && (
-          <IconButton onClick={onClose} size="small">
-            <ChevronLeftIcon />
-          </IconButton>
-        )}
-      </Box>
-    )
-  }
-)
-SidebarHeader.displayName = 'SidebarHeader'
-
-// SidebarContent
 interface SidebarContentProps {
   children: ReactNode
 }
 
 const SidebarContent = forwardRef<HTMLDivElement, SidebarContentProps>(
-  ({ children, ...props }, ref) => {
-    return (
-      <Box
-        ref={ref}
-        sx={{
-          flex: 1,
-          overflow: 'auto',
-          py: 1,
-        }}
-        {...props}
-      >
-        {children}
-      </Box>
-    )
-  }
+  ({ children, ...props }, ref) => (
+    <Box
+      ref={ref}
+      sx={{
+        flex: 1,
+        overflow: 'auto',
+        py: 1,
+      }}
+      {...props}
+    >
+      {children}
+    </Box>
+  )
 )
 SidebarContent.displayName = 'SidebarContent'
 
-// SidebarFooter
 interface SidebarFooterProps {
   children: ReactNode
 }
 
 const SidebarFooter = forwardRef<HTMLDivElement, SidebarFooterProps>(
-  ({ children, ...props }, ref) => {
-    return (
-      <Box
-        ref={ref}
-        sx={{
-          p: 2,
-          borderTop: 1,
-          borderColor: 'divider',
-        }}
-        {...props}
-      >
-        {children}
-      </Box>
-    )
-  }
+  ({ children, ...props }, ref) => (
+    <Box
+      ref={ref}
+      sx={{
+        p: 2,
+        borderTop: 1,
+        borderColor: 'divider',
+      }}
+      {...props}
+    >
+      {children}
+    </Box>
+  )
 )
 SidebarFooter.displayName = 'SidebarFooter'
 
-// SidebarNav
-interface SidebarNavProps {
-  items: SidebarItem[]
-  dense?: boolean
-}
-
-const SidebarNav = forwardRef<HTMLUListElement, SidebarNavProps>(
-  ({ items, dense = false, ...props }, ref) => {
-    const [openItems, setOpenItems] = useState<Set<string>>(new Set())
-
-    const toggleItem = (label: string) => {
-      setOpenItems(prev => {
-        const next = new Set(prev)
-        if (next.has(label)) {
-          next.delete(label)
-        } else {
-          next.add(label)
-        }
-        return next
-      })
-    }
-
-    const renderItem = (item: SidebarItem, depth: number = 0) => {
-      const hasChildren = item.children && item.children.length > 0
-      const isOpen = openItems.has(item.label)
-
-      return (
-        <Box key={item.label}>
-          <ListItem disablePadding>
-            <ListItemButton
-              onClick={() => {
-                if (hasChildren) {
-                  toggleItem(item.label)
-                } else if (item.onClick) {
-                  item.onClick()
-                }
-              }}
-              disabled={item.disabled}
-              sx={{
-                pl: 2 + depth * 2,
-                minHeight: dense ? 40 : 48,
-              }}
-            >
-              {item.icon && (
-                <ListItemIcon sx={{ minWidth: 36 }}>
-                  {item.icon}
-                </ListItemIcon>
-              )}
-              <ListItemText
-                primary={item.label}
-                primaryTypographyProps={{
-                  variant: dense ? 'body2' : 'body1',
-                  fontWeight: depth === 0 ? 500 : 400,
-                }}
-              />
-              {item.badge && (
-                <Box sx={{ mr: 1 }}>
-                  {item.badge}
-                </Box>
-              )}
-              {hasChildren && (isOpen ? <ExpandLess /> : <ExpandMore />)}
-            </ListItemButton>
-          </ListItem>
-          {hasChildren && (
-            <Collapse in={isOpen} timeout="auto" unmountOnExit>
-              <List component="div" disablePadding dense={dense}>
-                {item.children!.map(child => renderItem(child, depth + 1))}
-              </List>
-            </Collapse>
-          )}
-        </Box>
-      )
-    }
-
-    return (
-      <List ref={ref} dense={dense} {...props}>
-        {items.map(item => renderItem(item))}
-      </List>
-    )
-  }
-)
-SidebarNav.displayName = 'SidebarNav'
-
-// SidebarSection
-interface SidebarSectionProps {
-  title?: string
-  children: ReactNode
-}
-
-const SidebarSection = forwardRef<HTMLDivElement, SidebarSectionProps>(
-  ({ title, children, ...props }, ref) => {
-    return (
-      <Box ref={ref} sx={{ py: 1 }} {...props}>
-        {title && (
-          <Typography
-            variant="caption"
-            sx={{
-              px: 2,
-              py: 1,
-              display: 'block',
-              color: 'text.secondary',
-              fontWeight: 600,
-              textTransform: 'uppercase',
-              letterSpacing: '0.05em',
-            }}
-          >
-            {title}
-          </Typography>
-        )}
-        {children}
-      </Box>
-    )
-  }
-)
-SidebarSection.displayName = 'SidebarSection'
-
-// SidebarSeparator
-const SidebarSeparator = forwardRef<HTMLHRElement, Record<string, never>>(
-  (props, ref) => {
-    return <Divider ref={ref} sx={{ my: 1 }} {...props} />
-  }
-)
-SidebarSeparator.displayName = 'SidebarSeparator'
-
-// SidebarToggle - trigger to open sidebar on mobile
 interface SidebarToggleProps {
   onClick: () => void
 }
 
 const SidebarToggle = forwardRef<HTMLButtonElement, SidebarToggleProps>(
-  ({ onClick, ...props }, ref) => {
-    return (
-      <IconButton ref={ref} onClick={onClick} edge="start" {...props}>
-        <MenuIcon />
-      </IconButton>
-    )
-  }
+  ({ onClick, ...props }, ref) => (
+    <IconButton ref={ref} onClick={onClick} edge="start" {...props}>
+      <MenuIcon />
+    </IconButton>
+  )
 )
 SidebarToggle.displayName = 'SidebarToggle'
 
+const SidebarNav = forwardRef<HTMLUListElement, MenuItemListProps>((props, ref) => (
+  <MenuItemList ref={ref} {...props} />
+))
+SidebarNav.displayName = 'SidebarNav'
+
 export {
   Sidebar,
   SidebarHeader,
@@ -307,4 +126,4 @@ export {
   SidebarSeparator,
   SidebarToggle,
 }
-export type { SidebarItem, SidebarProps }
+export type { SidebarItem, SidebarProps, SidebarHeaderProps }
diff --git a/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar/Header.tsx b/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar/Header.tsx
new file mode 100644
index 000000000..cfe0fe23d
--- /dev/null
+++ b/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar/Header.tsx
@@ -0,0 +1,38 @@
+import { forwardRef, ReactNode } from 'react'
+import { Box, IconButton } from '@mui/material'
+import ChevronLeftIcon from '@mui/icons-material/ChevronLeft'
+
+interface SidebarHeaderProps {
+  children?: ReactNode
+  onClose?: () => void
+  showCloseButton?: boolean
+}
+
+const SidebarHeader = forwardRef<HTMLDivElement, SidebarHeaderProps>(
+  ({ children, onClose, showCloseButton = false, ...props }, ref) => {
+    return (
+      <Box
+        ref={ref}
+        sx={{
+          display: 'flex',
+          alignItems: 'center',
+          justifyContent: 'space-between',
+          p: 2,
+          minHeight: 64,
+        }}
+        {...props}
+      >
+        {children}
+        {showCloseButton && onClose && (
+          <IconButton onClick={onClose} size="small">
+            <ChevronLeftIcon />
+          </IconButton>
+        )}
+      </Box>
+    )
+  }
+)
+SidebarHeader.displayName = 'SidebarHeader'
+
+export { SidebarHeader }
+export type { SidebarHeaderProps }
diff --git a/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar/NavSections.tsx b/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar/NavSections.tsx
new file mode 100644
index 000000000..8e05ba355
--- /dev/null
+++ b/frontends/nextjs/src/components/ui/organisms/navigation/Sidebar/NavSections.tsx
@@ -0,0 +1,44 @@
+import { forwardRef, ReactNode } from 'react'
+import { Box, Divider, Typography } from '@mui/material'
+
+interface SidebarSectionProps {
+  title?: string
+  children: ReactNode
+}
+
+const SidebarSection = forwardRef<HTMLDivElement, SidebarSectionProps>(
+  ({ title, children, ...props }, ref) => {
+    return (
+      <Box ref={ref} sx={{ py: 1 }} {...props}>
+        {title && (
+          <Typography
+            variant="caption"
+            sx={{
+              px: 2,
+              py: 1,
+              display: 'block',
+              color: 'text.secondary',
+              fontWeight: 600,
+              textTransform: 'uppercase',
+              letterSpacing: '0.05em',
+            }}
+          >
+            {title}
+          </Typography>
+        )}
+        {children}
+      </Box>
+    )
+  }
+)
+SidebarSection.displayName = 'SidebarSection'
+
+const SidebarSeparator = forwardRef<HTMLHRElement, Record<string, never>>(
+  (props, ref) => {
+    return <Divider ref={ref} sx={{ my: 1 }} {...props} />
+  }
+)
+SidebarSeparator.displayName = 'SidebarSeparator'
+
+export { SidebarSection, SidebarSeparator }
+export type { SidebarSectionProps }