The 22-year-old Saints youth product has joined the Chairboys on a free transfer after spending four months on loan at Adams Park this season.
Gape has played 20 times for Gareth Ainsworth's team, scoring once.
He leaves Southampton after making one first-team appearance, against Everton in December 2014.
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League Two side Wycombe Wanderers have signed midfielder Dominic Gape from Premier League club Southampton on a two-and-a-half-year deal.