The large billboard on Warwick Road urged electors to vote for Cat Smith - Labour's candidate for Lancaster and Fleetwood, 70 miles away.
Labour's candidate for Carlisle is Lee Sherriff.
A Labour spokesman said the advertising company working for the Lancaster party branch had made the error.
The spokesman said: "This has now been removed. Carlisle Labour Party campaign were not involved in any way."
The candidates for the Carlisle constituency are:
The candidates for the Lancaster and Fleetwood constituency are:
Labour has admitted a mistake was made after a poster featuring the wrong election candidate was put up in Carlisle.