Last season's runners-up defeated Los Caimanes 2-0 thanks to second-half goals from Ramon Rodriguez and Cesar Ortiz, and secured the three points despite Juan Lojas' red card just after the half-hour mark.
Garcilaso lost the two-legged championship play-off 5-4 on penalties to Universitario last season and after finishing ninth in 2014's Apertura campaign have started the Clausura season in terrible form.
The Cusco-based club had just three points from five matches heading into Saturday's fixture against visiting Caimanes but the home side seemed inspired at their Estadio Inca Garcilaso de la Vega, launching several promising attacks in the opening stages of the match.
Luis Flores Villena's men had to survive a couple of tough moments in the first half, however, with goalkeeper Diego Carranza saving a spot-kick from Caimanes' Renzo Reanos after Lojas was sent off for conceding the penalty.
Garcilaso struck the opener in the 69th minute when Rodriguez converted from just inside the penalty area following a sharp passing move.
Ortiz doubled their advantage with a sharp half-volley from Rodriguez's clever knock-down six minutes later as the 10-man hosts moved to six points and 12th in the standings.
Garcilaso remain nine points adrift of leaders Melgar, however, after the Arequipa-based club won 1-0 at Leon de Huanuco on Sunday.
Alejandro Hohberg scored the winner in the 89th minute for Melgar as they maintained a three-point gap on Union Comercio, Alianza Lima and Universitario.
Comercio defeated Inti Gas 2-1, Universitario thrashed UTC Cajamarca 3-0 and Alianza drew 2-2 at Cesar Vallejo.
In a game that involved three red cards, including two to Alianza, the visitors led twice at Cesar Vallejo but striker Mauro Guevgeozian scored two own goals, after also opening the scoring for his team, to ensure the hosts claimed a point.
In other results, Sport Huancayo won 1-0 at San Simon, Juan Aurich defeated Cienciano by the same margin and Universidad San Martin's clash with Sporting Cristal was postponed.
