It's been more than 30 years since they last won the prize.
That came in 1979, when they also secured the Dublin Senior Football Championship.
The Mobhi 2012 package is also shaping up nicely, but one man, Senan Connell, said goodbye to all that as he waved a fond farewell to senior football.
A sustained burst of applause broke out for Senan as the Na Fianna captain, Paddy Quinn, hailed his magnificent contribution to the jersey.
Paddy accepted the trophy from the Dublin County Board chief, Andy Kettle. "This has been a long journey for us," mused Paddy.
"Two years ago we just survived relegation. Last year we lost the league final to St Jude's, so hopefully we can now use this success as a further stepping stone."
The winning manager, Mick Downes, agreed: "We were very disappointed having lost the league final last season. And similarly when we were beaten by Jude's this year in the championship quarter-final.
"But we re-grouped after that, and we set the league as our goal, and it's nice now to end the year with the bit of silverware."
Na Fianna certainly deserved it, although Syls kept on their heels and came with a late shout. Na Fianna led all the way. They engineered a brisk start and they maintained that tempo.
Their defence excelled. Full-back, Niall McGovern, was outstanding. He had a big job - curbing the elegant Miceal McCarthy. He did it superbly.
Once in the second period, McGovern, reading the flight of the ball perfectly, nipped in front of McCarthy and charged off down the pitch like Frankel.
The Malahide men just couldn't get enough decent ball into the forwards. And finding themselves 0-6 to 0-1 behind in the 12th minute, they were always chasing the game.
Tomo Brady impressed at centre half-forward. He made even more of an impact in the second period. Another Timberjack, Joey Boland, at centre half-back, kicked two valuable points.
The Na Fianna left half-back, Eoin Connolly, sent over three gems in the first period off his cultured left peg. That helped them to lead at the break, 0-8 to 0-5.
Sylvester's had found their voice approaching the interval, hitting four points on the trot from Nigel Dunne, McCarthy and Darren Clarke (2) to leave just one point between them on 24 minutes.
But then another left-footed free from the supremely accurate Captain Quinn and a Connolly curler enabled Na Fianna to enjoy that half-time cushion.
Soon enough, Syls, seeking a bright opening to the restart, found themselves trailing by four points, but then three on the bounce from Clarke (2) and Dunne kept the pot simmering nicely.
With 10 minutes left, there was still just a point between them. Then, on 53 minutes, a Hail Mary in towards the clubhouse goal broke loose and Paddy Quinn took full advantage - 1-11 to 0-10. That looked to be that.
Yet two minutes from the end, Syls got a free out on the right.
Alan Foy floated it in, and John Coughlan, steaming in on the back post, rose highest to fist it to the basket.
A point in it. Tense times now. Na Fianna held onto the ball, playing down the clock. Syls were hoping, praying, for one more chink of light. It didn't come. On the last whistle, the winners embraced like brothers who hadn't met in three decades.
SCORERS - Na Fianna: P Quinn 1-3 (0-2f), A Caffrey (2f), E Connolly 0-3 each, J Boland 0-2. St Sylvester's: D Clarke 0-7 (7f), J Coughlan 1-0, N Dunne 0-2, M McCarthy 0-1.
NA FIANNA: C McCarville; E Ledwidth, N McGovern, K Reilly; N Cooper, J Boland, E Connolly; J McGuirk, P Quinn; S Coughlan, T Brady, JJ Martin; B Downes, A Caffrey, D Quinn. Subs: K O'Connor for Coughlan (42); S Connell for Martin (50); C Duignan for D Quinn (56).
ST SYLVESTER'S: R Wallace; A Lawlor, B Sexton, R Walsh; G McArdle, K Cleere, G Hazley; R Hazley, P Bracken; R Cleere, M Brennan, E Fanning; M McCarthy, N Dunne, D Clarke. Subs: D Galvin for Walsh (ht); A Relihan for Fanning (39); A Foy for R Cleere (45); J Coughlan for R Hazley (47); C Daly for McCarthy (51).
REF: G McMahon (O'Dwyer's).