Two second-half goals from Sean Treacy helped Dublin defeat Offaly by 2-15 to 1-10 at Tullamore.
As well as Man of the Match Treacy, corner forward AJ Murphy (0-4, all in the second half) and corner back Eoghan O'Donnell were also outstanding for the winners, who trailed by five points in the first half but are provincial champions at this level for the sixth time, completing a magnificent minor and U21 double in 2016.
Seeking their first title in 16 yars, Offaly produced a spirited first-half display in front of 4,709 spectators to lead by 1-6 to 0-5 at the interval, with Oisin Kelly supplying the goal from a penalty.
The hosts got off to a flying start with points from Dylan Murray (free) and Johnny O'Toole-Greene - a screamer from way out the field - but the Dubs replied through Chris Bennett with a brace of frees in the fifth and tenth minutes.
Offaly and Dublin players scramble for the ball. ©INPHO/Tommy Dickson.
The 13th minute proved lucky for the Faithfuls as full forward Kelly netted a penalty to propel them into a three-point lead, 1-2 to 0-2. A smashing Conor Doughan free from inside his own half extended the home side's advantage
Late changes to the Dublin starting XV had seen attackers Cian Boland and Colm Ó Neill replaced by Eoghan Conroy and Rian McBride, but they couldn't get going and Offaly moved 1-4 to 0-2 ahead thanks to another Murray effort in the 22nd minute.
Bennett (free) and Cian MacGabhann - with the visitors' first (and only first-half) score from play! - edged the Dubs back within a goal with two minutes left before the short whistle, but Emmet Nolan made it double scores, 1-5 to 0-4. Centre forward Nolan's second consecutive score was a real beauty and Bennett closed the first-half scoring from a Dublin '65'.
AJ Murphy reduced the arrears within seconds of the restart and Treacy's excellent first goal levelled matters in the 32nd minute - 1-6 each and a magnificent start to the second half for the winners! Murray's third point (free) steadied the Faithful County and a Nolan free restored their two-point advantage with 38 minutes played.
Dublin celebrate with the trophy. ©INPHO/Ryan Byrne.
After Murphy grabbed his second point Treacy kicked his second goal of the game to propel the Dubs into the lead for the first time with 40 minutes elapsed, 2-7 to 1-8. Murray's free made it a one-point match again but Murphy, Jake Malone and Treacy ('65') had a point apiece to hand the Metropolitans a 2-10 to 1-9 advantage with ten minutes remaining.
Treacy (free) and Malone made it five points without reply and Liam Langton's 57th-minute point for the hosts was too little, too late as the exceptional Andrew Jamieson Murphy clipped over his fourth point a minute from time.
McBride and Sean O Riain tagged on late points as the Dubs recorded their fourth Leinster U21 HC final victory over Offaly.
Dublin - J Treacy; J Madden, E O'Donnell, C Hendricken; S Barrett, C MacGabhann (0-1), J Bellew; J Malone (0-2), M McCallion; A Jamieson Murphy (0-4), R McBride (0-1), E Conroy; S Treacy (2-2, 0-1f, 0-1'65), S O'Riain (0-1), C Bennett (0-4, 3f, 1'65). Subs: C Boland for M McCallion, C O'Neill for C Bennett, P O'Dea for C Hendricken, F O Riain Broin for J Malone, E McHugh for E Conroy.
Offaly - E Cahill; C Doughan (0-1f), D O'Toole Greene, P Delaney; D Healy, B Conneely, D Doughan; D Wyer, P Guinan; J O'Toole Greene, D Murray (0-5, 4f), R Hughes; A Cleary, E Nolan (0-3), O Kelly (1-0pen). Subs: C O'Brien for D Healy, C Freeman for A Cleary, JP Cleary for R Hughes, L Langton (0-1) for D Wyer, E Parlon for P Guinan.
Referee - A Devine.