diff --git a/packages/schema/src/tests/utils/idl.spec.ts b/packages/schema/src/tests/utils/idl.spec.ts
index 28f3310f8..afdf88e61 100644
--- a/packages/schema/src/tests/utils/idl.spec.ts
+++ b/packages/schema/src/tests/utils/idl.spec.ts
@@ -52,10 +52,10 @@ describe('idl', () => {
         expect(
           schemaToIdl({
             schema: Schema,
-            value: {username: 'David', status: {type: 'active', owner: 'abc'}}
+            value: {username: 'Hello', status: {type: 'active', owner: 'abc'}}
           })
         ).toEqual({
-          username: 'David',
+          username: 'Hello',
           status: {active: {owner: 'abc'}}
         });
       });
@@ -132,13 +132,94 @@ describe('idl', () => {
         expect(
           schemaFromIdl({
             schema: Schema,
-            value: {username: 'David', status: {active: {owner: 'abc'}}}
+            value: {username: 'Hello', status: {active: {owner: 'abc'}}}
           })
         ).toEqual({
-          username: 'David',
+          username: 'Hello',
           status: {type: 'active', owner: 'abc'}
         });
       });
     });
   });
+
+  describe('camel case', () => {
+    describe('object with camelCase fields', () => {
+      const Schema = z.object({firstName: z.string(), lastName: z.string()});
+
+      it('converts camelCase keys to snake_case', () => {
+        expect(
+          schemaToIdl({schema: Schema, value: {firstName: 'Hello', lastName: 'World'}})
+        ).toEqual({
+          first_name: 'Hello',
+          last_name: 'World'
+        });
+      });
+    });
+
+    describe('object with camelCase fields', () => {
+      const Schema = z.object({firstName: z.string(), lastName: z.string()});
+
+      it('converts snake_case keys back to camelCase', () => {
+        expect(
+          schemaFromIdl({schema: Schema, value: {first_name: 'Hello', last_name: 'World'}})
+        ).toEqual({
+          firstName: 'Hello',
+          lastName: 'World'
+        });
+      });
+    });
+
+    describe('nested object with camelCase fields', () => {
+      const Schema = z.object({
+        userId: z.string(),
+        userProfile: z.object({displayName: z.string()})
+      });
+
+      it('converts nested camelCase keys to snake_case', () => {
+        expect(
+          schemaToIdl({
+            schema: Schema,
+            value: {userId: 'abc', userProfile: {displayName: 'Hello'}}
+          })
+        ).toEqual({
+          user_id: 'abc',
+          user_profile: {display_name: 'Hello'}
+        });
+      });
+
+      it('converts nested snake_case keys back to camelCase', () => {
+        expect(
+          schemaFromIdl({
+            schema: Schema,
+            value: {user_id: 'abc', user_profile: {display_name: 'Hello'}}
+          })
+        ).toEqual({
+          userId: 'abc',
+          userProfile: {displayName: 'Hello'}
+        });
+      });
+    });
+  });
+
+  describe('snake_case fields', () => {
+    const Schema = z.object({first_name: z.string(), last_name: z.string()});
+
+    it('keeps snake_case keys unchanged in schemaToIdl', () => {
+      expect(
+        schemaToIdl({schema: Schema, value: {first_name: 'Hello', last_name: 'World'}})
+      ).toEqual({
+        first_name: 'Hello',
+        last_name: 'World'
+      });
+    });
+
+    it('keeps snake_case keys unchanged in schemaFromIdl', () => {
+      expect(
+        schemaFromIdl({schema: Schema, value: {first_name: 'Hello', last_name: 'World'}})
+      ).toEqual({
+        first_name: 'Hello',
+        last_name: 'World'
+      });
+    });
+  });
 });
diff --git a/packages/schema/src/utils/idl.ts b/packages/schema/src/utils/idl.ts
index bb6a997b8..b43bf4ce1 100644
--- a/packages/schema/src/utils/idl.ts
+++ b/packages/schema/src/utils/idl.ts
@@ -5,6 +5,10 @@ export interface IdlParams {
   value: unknown;
 }
 
+// Duplicate utils to avoid to reference library utils in schema
+const convertCamelToSnake = (str: string): string =>
+  str.replace(/([a-zA-Z])(?=[A-Z])/g, '$1_').toLowerCase();
+
 /**
  * Recursively converts a JavaScript value to its Candid IDL representation,
  * guided by a Zod schema.
@@ -53,7 +57,7 @@ export const schemaToIdl = ({schema, value}: IdlParams): unknown => {
   if (schema instanceof z.ZodObject) {
     return Object.fromEntries(
       Object.entries(schema._zod.def.shape).map(([k, t]) => [
-        k,
+        convertCamelToSnake(k),
         schemaToIdl({schema: t as z.core.$ZodType, value: (value as Record<string, unknown>)[k]})
       ])
     );
@@ -129,7 +133,10 @@ export const schemaFromIdl = ({schema, value}: IdlParams): unknown => {
     return Object.fromEntries(
       Object.entries(schema._zod.def.shape).map(([k, t]) => [
         k,
-        schemaFromIdl({schema: t as z.core.$ZodType, value: (value as Record<string, unknown>)[k]})
+        schemaFromIdl({
+          schema: t as z.core.$ZodType,
+          value: (value as Record<string, unknown>)[convertCamelToSnake(k)]
+        })
       ])
     );
   }