Assuming Prefect 3.x: use the orchestration client to try to read the deployment and handle the “not found” case. Async (recommended):

from prefect.client.orchestration import get_client
from prefect.exceptions import ObjectNotFound

async def deployment_exists(flow_name: str, deployment_name: str) -> bool:
    full_name = f"{flow_name}/{deployment_name}"  # format: flow/deployment
    async with get_client() as client:
        try:
            await client.read_deployment_by_name(full_name)
            return True
        except ObjectNotFound:
            return False

Synchronous (if you prefer blocking I/O):

from prefect.client.orchestration import SyncPrefectClient
from prefect.exceptions import ObjectNotFound

def deployment_exists_sync(flow_name: str, deployment_name: str) -> bool:
    full_name = f"{flow_name}/{deployment_name}"
    with SyncPrefectClient() as client:
        try:
            client.read_deployment_by_name(full_name)
            return True
        except ObjectNotFound:
            return False

If you already have the deployment ID:

from prefect.client.orchestration import get_client
from prefect.exceptions import ObjectNotFound

async def deployment_exists_by_id(deployment_id: str) -> bool:
    async with get_client() as client:
        try:
            await client.read_deployment(deployment_id)
            return True
        except ObjectNotFound:
            return False

Notes and docs: - Name format is

"<flow_name>/<deployment_name>"

(workspace is implied by your active profile): Read deployment by name - Read by ID: Read deployment - List deployments (if you prefer listing and filtering): List deployments