The Black Cats took a first-half lead when Ross Stewart headed home Elliot Embleton’s free-kick, and the Wearsiders appeared to be in control of the match when Aiden McGeady converted from the penalty spot 16 minutes from time.
But when Callum Morton pulled a goal back in the 81st minute it resulted in a nervy finish as Sunderland tried to hang on.
Fleetwood were then awarded a penalty for a shirt pull against Bailey Wright and Gerard Garner converted from the spot, sending goalkeeper Thorben Hoffman the wrong way.
The result means Sunderland have been knocked off the top of League One by Wigan following the Latics’ 4-1 win at Accrington Stanley.
Our chief football writer Phil Smith has delivered his verdict on how each player fared at Highbury Stadium.
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1. Thorben Hoffmann - 7
Showed his quality with a superb first-half save, moments before Stewart got the crucial opening goal. Distribution was solid throughout and his save shortly before the penalty was superb. 7 Photo: JPI Media
2. Carl Winchester - 6
Drove forward impressively throughout but had some difficult moments in the second half as Morton began to make threatening runs from the left wing. 6 Photo: JPI Media
3. Bailey Wright - 6
Started the game very well but did give Morton a few openings through the contest. 6 Photo: Frank Reid
4. Callum Doyle - 7
Played some excellent balls forward from the back, and generally defended well against a lively forward line. 7 Photo: JPI Media