Winger Chris Jebb knocked the vital conversion through the posts, adding to his earlier haul of two penalties and a conversion of team captain Shane Young's try.
For the Michael Hastings-skippered UCD side, winger Vasily Artemiev and lock Brian Cawley helped themselves to tries. Centre Killian Lett kicked eight points (two penalties and a conversion).
The last two Colours games had been won by UCD, with the two previous clashes producing a Trinity win and a draw.
DUBLIN UNIVERSITY: Paul Gillespie (The King's Hospital); Chris Jebb (Rathcoole C.S.), Conor Colclough (Belvedere College SJ), Richard Brady (Foyle & Londonderry), Colin Murphy (Belvedere College SJ); Andy Wallace (Terenure College), Edward Hamilton (Methodist College); Tristan Goodbody (Columbus College), Mark Murdock (CBC Monkstown) , James Gethings (Gonzaga College), Patrick Danahy (Stanford University), Colin McDonnell (CBS Naas), Max Cantrell (Blackrock College), Shane Young (The King's Hospital) (capt), Brian Coyle (Clongowes Wood College SJ).
UCD: Conor Quinn (Glenstal Abbey); Cian Aherne (Crescent College Limerick), Killian Lett (The King's Hospital), Niall Kearns (CBC Monkstown), Vasily Artemiev (Blackrock College); Michael Hastings (Wesley College) (capt), Dara Geraghty (Blackrock College), John A. Lee (Terenure College), Conor Geoghegan (St. Michael's College), Ben Barclay (Clongowes Wood College SJ), Brian Cawley (Blackrock College), Arthur Houlihan (Clongowes Wood College SJ), Matt Nagle (Glenstal Abbey), Kevin Croke (CPC Kilcullen), David Gilchrist (Belvedere College SJ).
Replacements: Robert Shanley (St. Michael's College), Simon Gillespie (Sligo Grammar School), Rory Allwright (Sandford Park School), Mark Flanagan (St. Finian's Mullingar), Paddy Conlon (Summerhill College Sligo), Brian Hall (Cistercian College Roscrea), Gavin Telford (The King's Hospital).
Referee: Dudley Phillips (Leinster)