The experienced 32 year-old originally signed for Sussex for the first half of the 2012 season and, after an impressive run of form in the County Championship this year, which has seen him take 24 wickets, the club have moved to snap him up after he announced his retirement from representing Queensland in the Australian first-class game.
He excelled on his Sussex debut against Lancashire in early May, taking nine wickets in the match, before taking six in their most recent first-class encounter against Surrey at Horsham.
Magoffin said: “I am very thankful to Sussex CCC, Mark Robinson and Michael Yardy, for all of their support so far this season, and having the faith in me to continue my first-class career with Sussex CCC, beyond the 2012 summer.
“I have had a wonderful time in my career with Western Australia, and most recently winning the Sheffield Shield with Queensland, and with an addition to our family due in December, this is the right time for my wife and I to relocate to the UK.
“I am looking forward to continuing to contribute to the team both on and off the field and hope to enjoy the same success with Sussex as I did with Queensland last year, and bring some silverware back to Hove”.
Sussex’s professional cricket manager Mark Robinson said: “Mags has fitted in really well in his time here. With overseas players increasingly difficult to find and the International calendar even busier next season with the Champions Trophy in our summer, we are delighted to have secured such a dependable and important player for the rest of the season and the next.”