London Irish made it 10 league wins from 10 in their bid to bounce back to the Premiership at the first attempt.
Jersey debutant Guy Armitage got the opening try, but Irish replied though David Paice and Richard Palframan scores from mauls.
Ben Ransom, Tom Fowlie and Paice, again, all touched down for the hosts after half-time.
Marc Thomas, George Watkins and Nick Haining tries were enough for a Jersey bonus point.
The Reds had gone into this first meeting between the clubs with barely enough recognised backs to field a proper side, and handed a debut to former London Irish centre Armitage who joined on loan this week.
He ran through for the opener - after a quick-tap penalty from scrum-half Sami Fisilau - to kick-start his Jersey try-scoring account within three minutes.
Ex-Jersey back Tommy Bell narrowed the deficit for the hosts with a penalty, before captain Paice scored from the maul after a long spell of pressure.
Sam Katz's penalty from his own half pulled the islanders level at 10-10 just before half-time, but there was still time for prop Palframan to power over from another maul with the final move of the half.
Ransom and Fowlie both grabbed scores early in the second period to put Irish in control, but with Ransom in the sin-bin, the Reds got their second try when Thomas went over from another maul.
Bell's penalty steadied the ship for the Championship leaders, but Jersey winger Watkins intercepted a cross-field kick to dart in and further cut the gap.
Paice then powered over for his second try at the other end before Bell's drop goal.
Haining though, made sure Jersey left the Madejski Stadium with a bonus point, picking up the ball from the back of a scrum and crashing over in the closing stages.
London Irish: Tonks; Cokanasiga, Fowlie, Williams, Ransom; Bell, Steele; Court, Paice (capt), Palframan, Lloyd, Sexton, Northcote-Green, Cowan, Nayalo
Replacements: Ellis, Elrington, Franks, De Chaves, Coman, McKibbin, Mulchrone
Jersey Reds: Katz; Watkins, Armitage, Davies, Dolan; McKinney, Fisilau; Thomas, Buckle, Kerrod, Campbell, Voss, Freeman (capt), Graham, Haining
Replacements: Macfarlane, McCarthy, Tampin, Kolo'ofa'i, Argyle, Doyle, Dudley.