The Ulster GAA Football Under-20 Championship, known simply as the Ulster Under-20 Championship, is an annual inter-county Gaelic football competition organised by the Ulster Council of the Gaelic Athletic Association (GAA).

It is the highest inter-county football competition for male players between the ages of 17 and 20 in the province of Ulster.

The final, currently held in March, serves as the culmination of a series of games played during a three-week period, and the results determine which team receives the J. J. Fahy Cup.

The winners of the Ulster final, like their counterparts in the other three provinces, advance to the semi-final stage of the All-Ireland series of games.

The most successful team of each decade, judged by number of Ulster Championship titles, is as follows: Top ten longest gaps between successive championship titles: