diff --git a/docs/development/plugins/expressions/public/kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.cumulative_sum.md b/docs/development/plugins/expressions/public/kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.cumulative_sum.md
new file mode 100644
index 0000000000000..ad1de0cc5f45b
--- /dev/null
+++ b/docs/development/plugins/expressions/public/kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.cumulative_sum.md
@@ -0,0 +1,11 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [kibana-plugin-plugins-expressions-public](./kibana-plugin-plugins-expressions-public.md) &gt; [ExpressionFunctionDefinitions](./kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.md) &gt; [cumulative\_sum](./kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.cumulative_sum.md)
+
+## ExpressionFunctionDefinitions.cumulative\_sum property
+
+<b>Signature:</b>
+
+```typescript
+cumulative_sum: ExpressionFunctionCumulativeSum;
+```
diff --git a/docs/development/plugins/expressions/public/kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.md b/docs/development/plugins/expressions/public/kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.md
index 914c5d6ebe2f6..d1703a1e019e6 100644
--- a/docs/development/plugins/expressions/public/kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.md
+++ b/docs/development/plugins/expressions/public/kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.md
@@ -17,6 +17,7 @@ export interface ExpressionFunctionDefinitions
 |  Property | Type | Description |
 |  --- | --- | --- |
 |  [clog](./kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.clog.md) | <code>ExpressionFunctionClog</code> |  |
+|  [cumulative\_sum](./kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.cumulative_sum.md) | <code>ExpressionFunctionCumulativeSum</code> |  |
 |  [font](./kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.font.md) | <code>ExpressionFunctionFont</code> |  |
 |  [kibana\_context](./kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.kibana_context.md) | <code>ExpressionFunctionKibanaContext</code> |  |
 |  [kibana](./kibana-plugin-plugins-expressions-public.expressionfunctiondefinitions.kibana.md) | <code>ExpressionFunctionKibana</code> |  |
diff --git a/docs/development/plugins/expressions/server/kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.cumulative_sum.md b/docs/development/plugins/expressions/server/kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.cumulative_sum.md
new file mode 100644
index 0000000000000..2fb8cde92e877
--- /dev/null
+++ b/docs/development/plugins/expressions/server/kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.cumulative_sum.md
@@ -0,0 +1,11 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [kibana-plugin-plugins-expressions-server](./kibana-plugin-plugins-expressions-server.md) &gt; [ExpressionFunctionDefinitions](./kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.md) &gt; [cumulative\_sum](./kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.cumulative_sum.md)
+
+## ExpressionFunctionDefinitions.cumulative\_sum property
+
+<b>Signature:</b>
+
+```typescript
+cumulative_sum: ExpressionFunctionCumulativeSum;
+```
diff --git a/docs/development/plugins/expressions/server/kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.md b/docs/development/plugins/expressions/server/kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.md
index 71cd0b98a68c2..05b4ddce4ccde 100644
--- a/docs/development/plugins/expressions/server/kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.md
+++ b/docs/development/plugins/expressions/server/kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.md
@@ -17,6 +17,7 @@ export interface ExpressionFunctionDefinitions
 |  Property | Type | Description |
 |  --- | --- | --- |
 |  [clog](./kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.clog.md) | <code>ExpressionFunctionClog</code> |  |
+|  [cumulative\_sum](./kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.cumulative_sum.md) | <code>ExpressionFunctionCumulativeSum</code> |  |
 |  [font](./kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.font.md) | <code>ExpressionFunctionFont</code> |  |
 |  [kibana\_context](./kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.kibana_context.md) | <code>ExpressionFunctionKibanaContext</code> |  |
 |  [kibana](./kibana-plugin-plugins-expressions-server.expressionfunctiondefinitions.kibana.md) | <code>ExpressionFunctionKibana</code> |  |
diff --git a/src/plugins/expressions/common/expression_functions/specs/cumulative_sum.ts b/src/plugins/expressions/common/expression_functions/specs/cumulative_sum.ts
index 4e2414a131af9..970015638794f 100644
--- a/src/plugins/expressions/common/expression_functions/specs/cumulative_sum.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/cumulative_sum.ts
@@ -62,7 +62,7 @@ function getBucketIdentifier(row: DatatableRow, groupColumns?: string[]) {
  * Edge cases:
  * * Will return the input table if `inputColumnId` does not exist
  * * Will throw an error if `outputColumnId` exists already in provided data table
- * * If `column` contains `null` or `undefined`, it will be ignored and overwritten with the cumulative sum of
+ * * If the row value contains `null` or `undefined`, it will be ignored and overwritten with the cumulative sum of
  *   all cells of the same series further up in the table.
  * * For all values besides `null` and `undefined`, the value will be cast to a number before it's added to the
  *   cumulative sum of the current series - if this results in `NaN` (like in case of objects), all cells of the
diff --git a/src/plugins/expressions/common/expression_functions/specs/tests/cumulative_sum.test.ts b/src/plugins/expressions/common/expression_functions/specs/tests/cumulative_sum.test.ts
index a8d06ab370f04..037b3ddc25f89 100644
--- a/src/plugins/expressions/common/expression_functions/specs/tests/cumulative_sum.test.ts
+++ b/src/plugins/expressions/common/expression_functions/specs/tests/cumulative_sum.test.ts
@@ -25,7 +25,7 @@ import { Datatable } from '../../../expression_types/specs/datatable';
 describe('interpreter/functions#cumulative_sum', () => {
   const fn = functionWrapper(cumulativeSum);
   const runFn = (input: Datatable, args: CumulativeSumArgs) =>
-    fn(input, args, {} as ExecutionContext);
+    fn(input, args, {} as ExecutionContext) as Datatable;
 
   it('calculates cumulative sum', () => {
     const result = runFn(
diff --git a/src/plugins/expressions/common/expression_functions/types.ts b/src/plugins/expressions/common/expression_functions/types.ts
index caaef541aefd5..fb1823e85b391 100644
--- a/src/plugins/expressions/common/expression_functions/types.ts
+++ b/src/plugins/expressions/common/expression_functions/types.ts
@@ -29,6 +29,7 @@ import {
   ExpressionFunctionVarSet,
   ExpressionFunctionVar,
   ExpressionFunctionTheme,
+  ExpressionFunctionCumulativeSum,
 } from './specs';
 import { ExpressionAstFunction } from '../ast';
 import { PersistableStateDefinition } from '../../../kibana_utils/common';
@@ -131,4 +132,5 @@ export interface ExpressionFunctionDefinitions {
   var_set: ExpressionFunctionVarSet;
   var: ExpressionFunctionVar;
   theme: ExpressionFunctionTheme;
+  cumulative_sum: ExpressionFunctionCumulativeSum;
 }
diff --git a/src/plugins/expressions/public/public.api.md b/src/plugins/expressions/public/public.api.md
index 3f74fe045dd2c..b5a64405aa062 100644
--- a/src/plugins/expressions/public/public.api.md
+++ b/src/plugins/expressions/public/public.api.md
@@ -377,6 +377,10 @@ export interface ExpressionFunctionDefinitions {
     //
     // (undocumented)
     clog: ExpressionFunctionClog;
+    // Warning: (ae-forgotten-export) The symbol "ExpressionFunctionCumulativeSum" needs to be exported by the entry point index.d.ts
+    //
+    // (undocumented)
+    cumulative_sum: ExpressionFunctionCumulativeSum;
     // Warning: (ae-forgotten-export) The symbol "ExpressionFunctionFont" needs to be exported by the entry point index.d.ts
     //
     // (undocumented)
diff --git a/src/plugins/expressions/server/server.api.md b/src/plugins/expressions/server/server.api.md
index 0c9e4af84f6a5..4d38d55e63726 100644
--- a/src/plugins/expressions/server/server.api.md
+++ b/src/plugins/expressions/server/server.api.md
@@ -349,6 +349,10 @@ export interface ExpressionFunctionDefinitions {
     //
     // (undocumented)
     clog: ExpressionFunctionClog;
+    // Warning: (ae-forgotten-export) The symbol "ExpressionFunctionCumulativeSum" needs to be exported by the entry point index.d.ts
+    //
+    // (undocumented)
+    cumulative_sum: ExpressionFunctionCumulativeSum;
     // Warning: (ae-forgotten-export) The symbol "ExpressionFunctionFont" needs to be exported by the entry point index.d.ts
     //
     // (undocumented)