diff --git a/docs/reference/esql/functions/description/locate.asciidoc b/docs/reference/esql/functions/description/locate.asciidoc
index e5a6fba512432..b3f9d2a1ad78e 100644
--- a/docs/reference/esql/functions/description/locate.asciidoc
+++ b/docs/reference/esql/functions/description/locate.asciidoc
@@ -2,4 +2,4 @@
 
 *Description*
 
-Returns an integer that indicates the position of a keyword substring within another string.
+Returns an integer that indicates the position of a keyword substring within another string. Returns `0` if the substring cannot be found. Note that string positions start from `1`.
diff --git a/docs/reference/esql/functions/kibana/definition/locate.json b/docs/reference/esql/functions/kibana/definition/locate.json
index 2097c90b41958..a9ddc8c52368a 100644
--- a/docs/reference/esql/functions/kibana/definition/locate.json
+++ b/docs/reference/esql/functions/kibana/definition/locate.json
@@ -2,7 +2,7 @@
   "comment" : "This is generated by ESQL's AbstractFunctionTestCase. Do no edit it. See ../README.md for how to regenerate it.",
   "type" : "eval",
   "name" : "locate",
-  "description" : "Returns an integer that indicates the position of a keyword substring within another string.",
+  "description" : "Returns an integer that indicates the position of a keyword substring within another string.\nReturns `0` if the substring cannot be found.\nNote that string positions start from `1`.",
   "signatures" : [
     {
       "params" : [
diff --git a/docs/reference/esql/functions/kibana/docs/locate.md b/docs/reference/esql/functions/kibana/docs/locate.md
index 75275068d3096..412832e9b1587 100644
--- a/docs/reference/esql/functions/kibana/docs/locate.md
+++ b/docs/reference/esql/functions/kibana/docs/locate.md
@@ -4,6 +4,8 @@ This is generated by ESQL's AbstractFunctionTestCase. Do no edit it. See ../READ
 
 ### LOCATE
 Returns an integer that indicates the position of a keyword substring within another string.
+Returns `0` if the substring cannot be found.
+Note that string positions start from `1`.
 
 ```
 row a = "hello"
diff --git a/x-pack/plugin/esql/qa/testFixtures/src/main/resources/meta.csv-spec b/x-pack/plugin/esql/qa/testFixtures/src/main/resources/meta.csv-spec
index f1f66a9cb990c..325b984c36d34 100644
--- a/x-pack/plugin/esql/qa/testFixtures/src/main/resources/meta.csv-spec
+++ b/x-pack/plugin/esql/qa/testFixtures/src/main/resources/meta.csv-spec
@@ -284,7 +284,7 @@ ip_prefix     |Truncates an IP to a given prefix length.
 least         |Returns the minimum value from multiple columns. This is similar to <<esql-mv_min>> except it is intended to run on multiple columns at once.
 left          |Returns the substring that extracts 'length' chars from 'string' starting from the left.
 length        |Returns the character length of a string.
-locate        |Returns an integer that indicates the position of a keyword substring within another string.
+locate        |Returns an integer that indicates the position of a keyword substring within another string. Returns `0` if the substring cannot be found. Note that string positions start from `1`.
 log           |Returns the logarithm of a value to a base. The input can be any numeric value, the return value is always a double.  Logs of zero, negative numbers, and base of one return `null` as well as a warning.
 log10         |Returns the logarithm of a value to base 10. The input can be any numeric value, the return value is always a double.  Logs of 0 and negative numbers return `null` as well as a warning.
 ltrim         |Removes leading whitespaces from a string.
diff --git a/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/Locate.java b/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/Locate.java
index ea088bdc412e8..f6eff2fcbd6b3 100644
--- a/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/Locate.java
+++ b/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/string/Locate.java
@@ -46,11 +46,10 @@ public class Locate extends EsqlScalarFunction implements OptionalArgument {
     private final Expression substr;
     private final Expression start;
 
-    @FunctionInfo(
-        returnType = "integer",
-        description = "Returns an integer that indicates the position of a keyword substring within another string.",
-        examples = @Example(file = "string", tag = "locate")
-    )
+    @FunctionInfo(returnType = "integer", description = """
+        Returns an integer that indicates the position of a keyword substring within another string.
+        Returns `0` if the substring cannot be found.
+        Note that string positions start from `1`.""", examples = @Example(file = "string", tag = "locate"))
     public Locate(
         Source source,
         @Param(name = "string", type = { "keyword", "text" }, description = "An input string") Expression str,