The 23-year-old was named in the starting line-up alongside compatriot Haashim Domingo for the 12th time this season, as Guimaraes faced off against 12th-placed Sporting Lisbon in Lisbon.
The visitors took the lead on the stroke of half-time, with the hosts levelling matters in the 68th minute to bring themselves back into the game.
Yet two minutes later Phete, who had not scored in two-and-a-half seasons at Guimaraes, was on hand to score his maiden goal for the club in what proved to be the winner in a 2-1 victory, just their fifth of the season.
Despite the three points, Guimaraes are still struggling in the relegation zone, sitting 19th in the Portuguese Second Division after 18 games played.
Elsewhere, two South Africans took to the field as Benfica and Braga faced off in their final match of 2017, with Thibang Cele named on the bench for the hosts while compatriot Luther Singh earned his 15th start for Braga.
Benfica took the lead four minutes before half-time, which would prove to be the only goal of the game, with Cele unfortunately not making it off the bench in his side’s victory while Singh was taken off in the second half.
The result boosts Benfica up to eighth on the log after 18 games, while Singh’s Braga slip down to 18th, one point above automatic relegation candidates Guimaraes.