Sheffield Wednesday received a 12-point deduction in August for breacging EFL spending rules, a penalty which was halved to six points upon appeal last week.
The club's off-field turmoil has been reflected in the performances on the pitch, having picked up just three wins from its opening 11 games to start the season.
After losing four games in a row, Sheffield regrouped with a win over Bournmemouth and a goalless draw against Milwall, but the recent revival wasn't enough to save Garry Monk's job.
"I feel the time is right to make a change and I wish Garry and his team all the best for the future," Owner Dejphon Chansiri said.
"I would like to say thank you for the time and effort Garry and his staff have committed to Sheffield Wednesday."