diff --git a/.changeset/light-turtles-yawn.md b/.changeset/light-turtles-yawn.md
new file mode 100644
index 0000000000..3f42fb0524
--- /dev/null
+++ b/.changeset/light-turtles-yawn.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-catalog-backend': patch
+---
+
+Fixed deprecated use of `substr` into `substring`.
diff --git a/plugins/catalog-backend/src/modules/core/PlaceholderProcessor.ts b/plugins/catalog-backend/src/modules/core/PlaceholderProcessor.ts
index ec432c5fdc..79fcee960c 100644
--- a/plugins/catalog-backend/src/modules/core/PlaceholderProcessor.ts
+++ b/plugins/catalog-backend/src/modules/core/PlaceholderProcessor.ts
@@ -107,7 +107,7 @@ export class PlaceholderProcessor implements CatalogProcessor {
         return [data, false];
       }
 
-      const resolverKey = keys[0].substr(1);
+      const resolverKey = keys[0].substring(1);
       const resolverValue = data[keys[0]];
 
       const resolver = this.options.resolvers[resolverKey];
diff --git a/plugins/catalog-backend/src/service/request/parseEntityFilterParams.ts b/plugins/catalog-backend/src/service/request/parseEntityFilterParams.ts
index 1ea5d44b2c..767a36ce71 100644
--- a/plugins/catalog-backend/src/service/request/parseEntityFilterParams.ts
+++ b/plugins/catalog-backend/src/service/request/parseEntityFilterParams.ts
@@ -63,9 +63,13 @@ export function parseEntityFilterString(
     const equalsIndex = statement.indexOf('=');
 
     const key =
-      equalsIndex === -1 ? statement : statement.substr(0, equalsIndex).trim();
+      equalsIndex === -1
+        ? statement
+        : statement.substring(0, equalsIndex).trim();
     const value =
-      equalsIndex === -1 ? undefined : statement.substr(equalsIndex + 1).trim();
+      equalsIndex === -1
+        ? undefined
+        : statement.substring(equalsIndex + 1).trim();
     if (!key) {
       throw new InputError(
         `Invalid filter, '${statement}' is not a valid statement (expected a string on the form a=b or a= or a)`,