Ian joined London Irish in July 2012 and has made 38 appearances scoring 212 points that includes two tries.
Ian Humphreys said: “I’ve thoroughly enjoyed the last two years at London Irish. The ambition, energy and resources the new ownership has bought to the Club is clear for everyone to see. With new training facilities and investment in the playing squad there is no doubt London Irish are at the start of a very exciting journey.
“Unexpectedly, the opportunity has arisen for me to return to Ulster and in the best interests of my family I have decided to accept. I’d like to thank everyone associated with the Club for making the last two years so memorable and look forward to watching London Irish realise their ambitions.”
Brian Smith, Exiles Director of Rugby added: “Ian has been a fantastic ambassador for our Club over the last two seasons and has given everything when he has worn the Club’s jersey. He’s made a family decision to return to Ulster where he’ll no doubt make a significant contribution. We wish Ian, Jenny and the girls all the best for the future.”