Gastelum announced the bout Tuesday afternoon on Twitter.
The youngest competitor in TUF history, Gastelum (6-0) looks to extend his unbeaten record following a stunning run to the finals of the TUF 17 middleweight tournament. Despite being the final pick of Team Sonnen, the 21-year-old prospect finished Bubba McDaniel, Collin Hart and Josh Samman in succession, before edging heavily-hyped Uriah Hall via split decision in the season's finale.
Meeting Gastelum at welterweight will be Thiago (15-5), a once promising contender who has fallen on hard times as of late.
After kicking off his UFC career with a 4-1 run, including a shocking knockout of Josh Koscheck, Thiago has now lost four or his last six outings dating back to mid-2010. Facing a three-fight losing streak, Thiago got back into the win column and potentially saved his job in his most recent contest, claiming a unanimous decision over Michel Prazeres at UFC on FX 8.