Both teams started off shakily although the crowd were behind both teams.
Seamer had the first chance of the game on three minutes but a nervy shot was comfortably saved by Nedley.
Seamer then dominated the next 10 minutes with Park unusually looking poor at the back, with constant pressure on Wiggins and co.
Skipper Lane rallied round the team and started to find more space in the midfield and after a chance went just wide from Belchamber, Fishburn started to get more and more confident.
And on 25 minutes, an excellent ball by Brennan fell to Belchamber who skipped past the keeper and slotted home past two defenders to put Park in the lead.
Seamer went looking for an equaliser but Park's defence started to look more solid with Jacques-Hale, Wiggins, Thistle and Hewison keeping a tight back line.
Fishburn nearly went two up just before half-time with nearly a carbon copy of the first goal but Belchamber just shot wide.
Park went into the second half knowing it was their game to lose and Seamer piled on the pressure, with Fishburn hoping to catch them on the counter-attack.
And that's just what Park did five minutes in when Belchamber looped a ball over the top for Waterfield to time his run well and slot into the far corner.
Two minutes later, Seamer could have been back in the game after a glancing header from a corner looked certain to find the net but Thistle cleared off the line.
On 70 minutes, Seamer did pull one back after a lapse of concentration from the defence saw a volley on the edge of the box find its way into the back of the net.
Park brought on subs to freshen things up and re-shuffled a few positions to try to find another goal to kill the game off.
It came 10 minutes from the end as Brennan found himself one-on-one to finish emphatically to keep the two-goal advantage.
Then in stoppage time, a free-kick from Lane was smashed in to the bottom corner by Brennan for his second and Park's fourth.
The final whistle sounded to secure Fishburn under 16s' first trophy – a brilliant overall team performance in front of a small crowd.
Thank you to all the players and supporters for a great day and a great season.
Man of the match: Shane Belchamber – almost perfect game as he bagged his 38th goal of the season.
Result: Fishburn Park U16s 4 Seamer 1