Magoffin joined Sussex two years ago and has been leading wicket-taker for the county in 2012 and 2013 in the LV= County Championship.
The 33-year-old Queenslander claimed 63 scalps at an average of 21.49 earlier this year and is overjoyed to extend his stay at Hove.
"I am delighted that Sussex have asked me to continue at the club for the 2014 season," he said.
"The last two years have been very enjoyable and I hope to continue to perform well for Sussex this coming season."
Magoffin's efforts helped Sussex finish third in the championship and captain Ed Joyce believes keeping the seamer at Hove is a major coup.
"It's great news to have Mags around for at least another season," said Joyce. "He's led our attack brilliantly in four-day cricket in the last couple of years and has been one of the best performers in county cricket over that period as well.
"He is certainly a man in demand so to get his signature for another season is a relief."