Sheehan, 39, was named as Swansea boss on a permanent three-year deal in April following a successful period as caretaker from February.
Swansea were in danger of being dragged into a Championship relegation battle when Sheehan succeeded Luke Williams on a temporary basis but the Welsh club took 24 points from his 13 games in charge last term to finish 11th.
This season, however, they are 18th, with six defeats and four wins from 15 matches, and were booed off at home at half-time and full-time of the defeat to Ipswich.
Their total of 17 points from their first 15 games of a league campaign being their worst return since relegation from the top flight in 2018.
Sheehan was heavily backed in the summer transfer window as Swansea’s new ownership group, led by Brett Cravatt and Jason Cohen, showing their intent on getting the club in a position to challenge for a top-flight return.
Adam Idah, Marko Stamenic, Zeidane Inoussa and Ethan Galbraith were among those to command hefty transfer fees.
But they were unable to convert the early-season optimism at the club into results, with their attacking output under Sheehan in particular being heavily criticised.
Sheehan was initially expected to oversee the trip to Bristol City after the international break, but the club have now decided to go in a different direction.
It remains to be seen who City will turn to for a replacement.
Swansea City owners Brett Cravatt and Jason Cohen said:
“Alan has been instrumental in helping improve the club through two periods of time. Alan has a tireless work ethic, an honest approach, and a positive attitude. He has put his full effort into the job on behalf of the club.
“The club would like to place on record its thanks to Alan for all of his hard work during his time at Swansea City. We wish Alan and his family all the best for the future.”
[Lead image: Swansea City FC]
