Short answer: no. In Prefect 3.x, both flow IDs and flow run IDs are system-generated UUIDs and cannot be customized. What you can customize: - Flow name: set via the

@flow

decorator’s

name

parameter - Flow run name: set via the

@flow

decorator’s

flow_run_name

or when creating a run via the API/client - Idempotency: use

idempotency_key

when creating runs to deduplicate requests Examples:

from prefect import flow

@flow(name="my-custom-flow-name")
def my_flow():
    return "hello"

Create a flow run programmatically with a custom name and idempotency key:

import asyncio
from prefect.client.orchestration import get_client
from prefect.client.schemas.actions import FlowRunCreate

async def trigger():
    async with get_client() as client:
        flow_id = "00000000-0000-0000-0000-000000000000"  # replace with your flow's ID
        fr = await client.create_flow_run(
            FlowRunCreate(
                flow_id=flow_id,
                name="orders-etl-2025-11-05",
                idempotency_key="orders-etl-2025-11-05"
            )
        )
        print(fr.id)

asyncio.run(trigger())

References: - Flow decorator API: prefect.flows API - Create flow run (REST): Create Flow Run REST API - Custom metadata (names, tags, labels): Custom metadata guide If you had something specific in mind by “custom flow ID” (e.g., aligning with an external system’s identifier), let me know your use case—there may be a pattern using names, labels, or artifacts that fits.