Skipper Conor O'Gorman claimed 4 wickets for 46 runs as his team held their nerve in the crucial encounter, dismissing Scotland for 191 as they chased an Irish target of 214.
Spinners Varun Chopra (2-25), and Morgan Topping (1-26), played a vitall supporting role as they conceded just 51 runs in their combined 20 overs in the crucial middle overs.
Jamie Crawley (34), Finlay McCreath (30) and Rory Johnston (29) had taken Scotland to 110 for 3, but O'Gorman's wickets coupled with athletic Irish fielding, which saw two run outs, proved decisive in the final analysis.
Earlier, North County's Jamie Grassi had given the Irish innings an explosive start, hitting a run a ball 59, which included 5 fours and 4 sixes, wresting back the initiative from their opponents after the early wickets of Sam Murphy and Sean Currie.
Solid middle order contributions from Stuart Nelson (41), Graham Kennedy (27), Conor O'Gorman (21) and Harry Tector (19) took the Irish total to 214, despite a late collapse which saw their last four wickets fall for just ten runs.
Earlier in the week Ireland had recorded comfortable wins over Netherlands, Jersey and Guernsey, so finish top of the table with 8 points, ahead of Guernsey (4), Scotland (4), Netherlands (2), and Jersey (2).
Grassi topped the run scoring charts with 190, while Varyn Chopra finished third in the bowling stakes, taking 7 wickets in the 3 matches he played.
ICC EUROPE UNDER 15 CHAMPIONSHIPS
At Rugby,
IRELAND 214 all out (Jamie Grassi 59, Stuart Nelson 41, Graham Kennedy 27 Conor O'Gorman 21, Oliver Brown 4-18)
SCOTLAND 191 all out (45.4 overs, Jamie Crawley 34, Finlay McCreath 30, Rory Johnston 29, Conor O'Gorman 4-46, Varun Chopra 2-25).
Ireland won by 23 runs and are champions