Centre Ciaran Gaffney, who made his senior debut in the Guinness PRO12 last month, opened the scoring for the home side just before the break with sub academy outhalf Luke Carty kicking the conversion.
The outhalf wasn’t up to the tee again until the 77th minute when Sean Masterson, younger brother of senior player Eoghan, crossed for the last score of the game.
London Irish, unbeaten this season, now progress to the quarter final of the B&I Cup while the Eagles must travel to Cornwall next weekend in search of their first win in the campaign.
Connacht Eagles: 15 Josh Rowland, 14 Matthew Byrne, 13 Ciaran Gaffney, 12 Kieran Joyce, 11 Adam Leavy, 10 Luke Carty, 9 Conor McKeon, 1 Jack Dinneen, 2 Shane O’Hehir, 3 Dominic Robertson-McCoy, 4 Cillian Gallagher, 5 Danny Qualter, 6 Rory Moloney, 7 Josh Pim, 8 Marc Kelly
Replacements: 16 Conor Kyne, 17 Saba Meunargia, 18 Cian Romaine, 19 Sean Masterson, 20 Stephen Kerins, 21 Morgan Codyre, 22 Joe Murphy
London Irish: 15 Tom Parton, 14 Matt Williams, 13 Ciaran Hearn, 12 Ross Neal (Johnny Williams, 65), 11 Ben Ransom, 10 Theo Brophy Clews (Jacob Atkins, 60), 9 Scott Steele, 1 Harry Elrington, 2 Todd Gleave, 3 Ollie Hoskins, 4 Jerry Sexton (Will Lloyd, 60), 5 Josh McNally, 6 Joe Trayfoot (Luke Narraway, 65), 7 Conor Gilsenan (c), 8 Senitiki Nayalo
Replacements: 16 Ollie Adams, 17 Austin Hay, 18 Will Lloyd, 19 Luke Narraway, 20 Rory Brand, 21 Johnny Williams, 22 Jacob Atkins