The Connacht side, inspired by Ailbhe Clancy, were five ahead in the early stages of the second half but Tyrone rallied and made them work for the win.
Both sides were guilty of missing chances in the opening minutes with Leitrim creating two goal opportunities.
Maria Canavan kicked the game’s first score in the fifth minute but Leitrim finally got off the mark in the 12th minute when Muireann Devaney passed to Laura O’Dowd and she finished to the net.
Clancy set Devaney up minutes later for a fine point to put three between the sides.
Tyrone got on top and Aoife Horisk grabbed two goals for the Ulster side in the space of six minutes. The Errigal Ciarán clubwoman added a point while Chloe McCaffrey fired over a free to give Tyrone a five point lead in the 21st minute.
Michelle Guckian got a much needed score for Leitrim from a free in the 22nd minute and she then forced a good save from Tyrone keeper Amelia Coyle, but in the 25th minute Guckian’s free was caught by Clancy and she fired to the net.
O’Dowd and Guckian (free) kicked over points as Leitrim went in at the break two points ahead, 2-5 to 2-2.
Leitrim started the second half like they had ended the first with Guckian (free) and Clancy hitting points to extend the lead to four points in the 33rd minute. Tyrone were guilty of poor shot selection in the opening exchanges of the second half.
Guckian kicked another free in the 36th minute but after 18 minutes without a score, Tyrone substitute Sorcha Gormley hit a neat point in the 39th minute and Horisk followed up with a point, but Leitrim cancelled those scores with excellent points from Guckian and Clancy.
In the 45th minute, Tyrone’s Joanne Barrett was sin-binned when she brought down Devaney. Up stepped Clancy and she made no mistake from the penalty spot and O’Dowd kicked over a lovely point minutes later to stretch Leitrim’s lead to seven points.
Tyrone were back in the game in the 49th when Aoibhinn McHugh got in for a goal and two points from McCaffrey, one of them a free, and an Emma Conroy effort cut the gap to one in the 59th minute, but Leitrim hung on to bring the Mary Quinn Memorial Cup home.
Scorers – Leitrim: A Clancy 2-3 (1-0pen), M Guckian 0-5 (4fs), L O’Dowd 1-2, M Devaney 0-1.
Tyrone: A Horisk 2-2, C McCaffrey 0-4 (2fs), A McHugh1-0, M Canavan, E Conroy, E McNamee, S Gormley 0-1 each.
LEITRIM: M Monaghan; E Quigley, C Tyrell, C Owens; S Reynolds, K Bruen, Elise Bruen; N Tighe, M Guckian; O Flynn, L O’Dowd, M Devaney; A Clancy, S Quinn, A Redican.
Subs: L Fox for Quinn (37), B O’Rourke for Guckian (49), M Murphy for Quigley (57).
TYRONE: A Coyle; J Lyons, J Barrett, E Quinn; C Daly, M Corrigan, C Campbell; A McHugh, M Mallon; A Grimes, A Horisk, E J Gervin; C McCaffrey, Z Loughran, M Canavan.
Subs: S Gormley for Loughran (35), E Mulgrew for Canavan (47), E McNamee for Grimes (44), Grimes for McNamee (53), McNamee for Mallon (54), E Conroy for Gervin (54).
Referee: Barry Redmond (Wexford)