On May 13, Solis tasted defeat as a professional for the first time, when facing debutant Santiago Rosas, who outpointed him over four rounds at San Juan.
Solis took off almost a year after the second loss to Rosas but re-emerged in the last seven months of 1973 fighting five times during that span, going 3-1-1 in those bouts, defeating 1-5 Gilberto Mendez on May 12 by a fourth-round knockout at the Country Club Stadium in Carolina, debuting Rolando Martinez by six-round decision at Isabela on July 14, and 8-2 Enrique Alonso by a ten-round decision November 30 at San Juan.
Solis' two 1974 bouts were significant because they were against Benjamin Ortiz, another Puerto Rican and who also fought multiple world class fighters.
Solis only had two bouts in 1977, but they were important ones: on July 11, he outpointed 28-1, world ranked Hector Medina over ten rounds at San Juan.
Solis went up in weight to the Junior Lightweight division for this bout, held at Somoza Stadium in Managua, Nicaragua on December 18.
Enrique Solis returned his name to the winning column on his next fight, when he faced Felix Trinidad Sr. on December 18 in San Juan, knocking out the former Puerto Rican national Featherweight titlist in round nine.
Solis took 1980 off but returned in 1981 to defeat 9-7-3 Heriberto Olivares by a ten-round decision in San Juan, after which he was granted a shot at the USBA's Super Featherweight title against the undefeated, 17-0 John Verderosa.