diff --git a/docs/changelog.rst b/docs/changelog.rst
index 9d253f522..ac0af4400 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -43,6 +43,8 @@ Detailed list of changes
 - Wayland: Fix a regression in the previous release that caused mouse cursor
   animation and keyboard repeat to stop working when switching seats (:iss:`5188`)
 
+- Allow resizing windows created in session files (:pull:`5196`)
+
 
 0.25.2 [2022-06-07]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/docs/overview.rst b/docs/overview.rst
index 84fe0d9a3..ea55921f2 100644
--- a/docs/overview.rst
+++ b/docs/overview.rst
@@ -161,6 +161,8 @@ option in :file:`kitty.conf`. For example:
     # Set the --class for the new OS window
     os_window_class mywindow
     launch sh
+    # Resize the current window (see the resize_window action for details)
+    resize_window wider 2
     # Make the current window the active (focused) window
     focus
     launch emacs
diff --git a/kitty/session.py b/kitty/session.py
index 2a1dc776a..71ab71e0c 100644
--- a/kitty/session.py
+++ b/kitty/session.py
@@ -3,7 +3,7 @@
 
 import shlex
 import sys
-from typing import TYPE_CHECKING, Generator, Iterator, List, Optional, Union
+from typing import TYPE_CHECKING, Generator, Iterator, List, Optional, Union, Tuple
 
 from .cli_stub import CLIOptions
 from .constants import kitty_exe
@@ -16,6 +16,7 @@ from .utils import log_error, resolved_shell
 
 if TYPE_CHECKING:
     from .window import CwdRequest
+    from .launch import LaunchSpec
 
 
 def get_os_window_sizing_data(opts: Options, session: Optional['Session'] = None) -> WindowSizeData:
@@ -26,11 +27,21 @@ def get_os_window_sizing_data(opts: Options, session: Optional['Session'] = None
     return WindowSizeData(sizes, opts.remember_window_size, opts.single_window_margin_width, opts.window_margin_width, opts.window_padding_width)
 
 
+ResizeSpec = Tuple[str, int]
+
+
+class WindowSpec:
+
+    def __init__(self, launch_spec: Union['LaunchSpec', 'SpecialWindowInstance']):
+        self.launch_spec = launch_spec
+        self.resize_spec: Optional[ResizeSpec] = None
+
+
 class Tab:
 
     def __init__(self, opts: Options, name: str):
-        from .launch import LaunchSpec
-        self.windows: List[Union[LaunchSpec, 'SpecialWindowInstance']] = []
+        self.windows: List[WindowSpec] = []
+        self.pending_resize_spec: Optional[ResizeSpec] = None
         self.name = name.strip()
         self.active_window_idx = 0
         self.enabled_layouts = opts.enabled_layouts
@@ -70,11 +81,25 @@ class Session:
         if t.next_title and not spec.opts.window_title:
             spec.opts.window_title = t.next_title
         spec.opts.cwd = spec.opts.cwd or t.cwd
-        t.windows.append(spec)
+        t.windows.append(WindowSpec(spec))
         t.next_title = None
+        if t.pending_resize_spec is not None:
+            t.windows[-1].resize_spec = t.pending_resize_spec
+            t.pending_resize_spec = None
+
+    def resize_window(self, args: List[str]) -> None:
+        steps = 1
+        if len(args) > 1:
+            steps = int(args[1])
+        t = self.tabs[-1]
+        spec = args[0], steps
+        if t.windows:
+            t.windows[-1].resize_spec = spec
+        else:
+            t.pending_resize_spec = spec
 
     def add_special_window(self, sw: 'SpecialWindowInstance') -> None:
-        self.tabs[-1].windows.append(sw)
+        self.tabs[-1].windows.append(WindowSpec(sw))
 
     def focus(self) -> None:
         self.active_tab_idx = max(0, len(self.tabs) - 1)
@@ -95,7 +120,7 @@ def parse_session(raw: str, opts: Options) -> Generator[Session, None, None]:
         from .tabs import SpecialWindow
         for t in ans.tabs:
             if not t.windows:
-                t.windows.append(SpecialWindow(cmd=resolved_shell(opts)))
+                t.windows.append(WindowSpec(SpecialWindow(cmd=resolved_shell(opts))))
         return ans
 
     ans = Session()
@@ -132,6 +157,8 @@ def parse_session(raw: str, opts: Options) -> Generator[Session, None, None]:
                 ans.os_window_size = WindowSizes(WindowSize(*w), WindowSize(*h))
             elif cmd == 'os_window_class':
                 ans.os_window_class = rest
+            elif cmd == 'resize_window':
+                ans.resize_window(rest.split())
             else:
                 raise ValueError(f'Unknown command in session file: {cmd}')
     yield finalize_session(ans)
diff --git a/kitty/tabs.py b/kitty/tabs.py
index 334eb490a..a51e15961 100644
--- a/kitty/tabs.py
+++ b/kitty/tabs.py
@@ -168,12 +168,16 @@ class Tab:  # {{{
         self.mark_tab_bar_dirty()
 
     def startup(self, session_tab: 'SessionTab') -> None:
-        for cmd in session_tab.windows:
-            if isinstance(cmd, SpecialWindowInstance):
-                self.new_special_window(cmd)
+        for window in session_tab.windows:
+            spec = window.launch_spec
+            if isinstance(spec, SpecialWindowInstance):
+                self.new_special_window(spec)
             else:
                 from .launch import launch
-                launch(get_boss(), cmd.opts, cmd.args, target_tab=self, force_target_tab=True)
+                launch(get_boss(), spec.opts, spec.args, target_tab=self, force_target_tab=True)
+            if window.resize_spec is not None:
+                self.resize_window(*window.resize_spec)
+
         self.windows.set_active_window_group_for(self.windows.all_windows[session_tab.active_window_idx])
 
     def serialize_state(self) -> Dict[str, Any]: