diff --git a/apps/sim/executor/handlers/workflow/workflow-handler.ts b/apps/sim/executor/handlers/workflow/workflow-handler.ts
index 6a6877548e..994daa9f6b 100644
--- a/apps/sim/executor/handlers/workflow/workflow-handler.ts
+++ b/apps/sim/executor/handlers/workflow/workflow-handler.ts
@@ -12,6 +12,7 @@ import type {
 } from '@/executor/types'
 import { buildAPIUrl, buildAuthHeaders } from '@/executor/utils/http'
 import { parseJSON } from '@/executor/utils/json'
+import { lazyCleanupInputMapping } from '@/executor/utils/lazy-cleanup'
 import { Serializer } from '@/serializer'
 import type { SerializedBlock } from '@/serializer/types'
 import { useWorkflowRegistry } from '@/stores/workflows/registry/store'
@@ -86,7 +87,15 @@ export class WorkflowBlockHandler implements BlockHandler {
         const normalized = parseJSON(inputs.inputMapping, inputs.inputMapping)
 
         if (normalized && typeof normalized === 'object' && !Array.isArray(normalized)) {
-          childWorkflowInput = normalized as Record<string, any>
+          // Perform lazy cleanup: remove orphaned fields from inputMapping
+          // that no longer exist in the child workflow's inputFormat
+          const cleanedMapping = await lazyCleanupInputMapping(
+            ctx.workflowId || 'unknown',
+            block.id,
+            normalized,
+            childWorkflow.rawBlocks || {}
+          )
+          childWorkflowInput = cleanedMapping as Record<string, any>
         } else {
           childWorkflowInput = {}
         }
@@ -209,6 +218,7 @@ export class WorkflowBlockHandler implements BlockHandler {
       name: workflowData.name,
       serializedState: serializedWorkflow,
       variables: workflowVariables,
+      rawBlocks: workflowState.blocks,
     }
   }
 
@@ -281,6 +291,7 @@ export class WorkflowBlockHandler implements BlockHandler {
       name: wfData?.name || DEFAULTS.WORKFLOW_NAME,
       serializedState: serializedWorkflow,
       variables: workflowVariables,
+      rawBlocks: deployedState.blocks,
     }
   }
 
diff --git a/apps/sim/executor/utils/lazy-cleanup.ts b/apps/sim/executor/utils/lazy-cleanup.ts
new file mode 100644
index 0000000000..b55e02d3c3
--- /dev/null
+++ b/apps/sim/executor/utils/lazy-cleanup.ts
@@ -0,0 +1,163 @@
+import { db } from '@sim/db'
+import { workflowBlocks } from '@sim/db/schema'
+import { and, eq } from 'drizzle-orm'
+import { createLogger } from '@/lib/logs/console/logger'
+
+const logger = createLogger('LazyCleanup')
+
+/**
+ * Extract valid field names from a child workflow's start block inputFormat
+ *
+ * @param childWorkflowBlocks - The blocks from the child workflow state
+ * @returns Set of valid field names defined in the child's inputFormat
+ */
+function extractValidInputFieldNames(childWorkflowBlocks: Record<string, any>): Set<string> | null {
+  const validFieldNames = new Set<string>()
+
+  const startBlock = Object.values(childWorkflowBlocks).find((block: any) => {
+    const blockType = block?.type
+    return blockType === 'start_trigger' || blockType === 'input_trigger' || blockType === 'starter'
+  })
+
+  if (!startBlock) {
+    logger.debug('No start block found in child workflow')
+    return null
+  }
+
+  const inputFormat =
+    (startBlock as any)?.subBlocks?.inputFormat?.value ??
+    (startBlock as any)?.config?.params?.inputFormat
+
+  if (!Array.isArray(inputFormat)) {
+    logger.debug('No inputFormat array found in child workflow start block')
+    return null
+  }
+
+  // Extract field names
+  for (const field of inputFormat) {
+    if (field?.name && typeof field.name === 'string') {
+      const fieldName = field.name.trim()
+      if (fieldName) {
+        validFieldNames.add(fieldName)
+      }
+    }
+  }
+
+  return validFieldNames
+}
+
+/**
+ * Clean up orphaned inputMapping fields that don't exist in child workflow's inputFormat.
+ * This is a lazy cleanup that only runs at execution time and only persists if changes are needed.
+ *
+ * @param parentWorkflowId - The parent workflow ID
+ * @param parentBlockId - The workflow block ID in the parent
+ * @param currentInputMapping - The current inputMapping value from the parent block
+ * @param childWorkflowBlocks - The blocks from the child workflow
+ * @returns The cleaned inputMapping (only different if cleanup was needed)
+ */
+export async function lazyCleanupInputMapping(
+  parentWorkflowId: string,
+  parentBlockId: string,
+  currentInputMapping: any,
+  childWorkflowBlocks: Record<string, any>
+): Promise<any> {
+  try {
+    if (
+      !currentInputMapping ||
+      typeof currentInputMapping !== 'object' ||
+      Array.isArray(currentInputMapping)
+    ) {
+      return currentInputMapping
+    }
+
+    const validFieldNames = extractValidInputFieldNames(childWorkflowBlocks)
+
+    if (!validFieldNames || validFieldNames.size === 0) {
+      logger.debug('Child workflow has no inputFormat fields, skipping cleanup')
+      return currentInputMapping
+    }
+
+    const orphanedFields: string[] = []
+    for (const fieldName of Object.keys(currentInputMapping)) {
+      if (!validFieldNames.has(fieldName)) {
+        orphanedFields.push(fieldName)
+      }
+    }
+
+    if (orphanedFields.length === 0) {
+      return currentInputMapping
+    }
+
+    const cleanedMapping: Record<string, any> = {}
+    for (const [fieldName, fieldValue] of Object.entries(currentInputMapping)) {
+      if (validFieldNames.has(fieldName)) {
+        cleanedMapping[fieldName] = fieldValue
+      }
+    }
+
+    logger.info(
+      `Lazy cleanup: Removing ${orphanedFields.length} orphaned field(s) from inputMapping in workflow ${parentWorkflowId}, block ${parentBlockId}: ${orphanedFields.join(', ')}`
+    )
+
+    persistCleanedMapping(parentWorkflowId, parentBlockId, cleanedMapping).catch((error) => {
+      logger.error('Failed to persist cleaned inputMapping:', error)
+    })
+
+    return cleanedMapping
+  } catch (error) {
+    logger.error('Error in lazy cleanup:', error)
+    return currentInputMapping
+  }
+}
+
+/**
+ * Persist the cleaned inputMapping to the database
+ *
+ * @param workflowId - The workflow ID
+ * @param blockId - The block ID
+ * @param cleanedMapping - The cleaned inputMapping value
+ */
+async function persistCleanedMapping(
+  workflowId: string,
+  blockId: string,
+  cleanedMapping: Record<string, any>
+): Promise<void> {
+  try {
+    await db.transaction(async (tx) => {
+      const [block] = await tx
+        .select({ subBlocks: workflowBlocks.subBlocks })
+        .from(workflowBlocks)
+        .where(and(eq(workflowBlocks.id, blockId), eq(workflowBlocks.workflowId, workflowId)))
+        .limit(1)
+
+      if (!block) {
+        logger.warn(`Block ${blockId} not found in workflow ${workflowId}, skipping persistence`)
+        return
+      }
+
+      const subBlocks = (block.subBlocks as Record<string, any>) || {}
+
+      if (subBlocks.inputMapping) {
+        subBlocks.inputMapping = {
+          ...subBlocks.inputMapping,
+          value: cleanedMapping,
+        }
+
+        // Persist updated subBlocks
+        await tx
+          .update(workflowBlocks)
+          .set({
+            subBlocks: subBlocks,
+            updatedAt: new Date(),
+          })
+          .where(and(eq(workflowBlocks.id, blockId), eq(workflowBlocks.workflowId, workflowId)))
+
+        logger.info(`Successfully persisted cleaned inputMapping for block ${blockId}`)
+      }
+    })
+  } catch (error) {
+    logger.error('Error persisting cleaned mapping:', error)
+    throw error
+  }
+}