His promoter Bob Arum stated "The last two-time gold medalist that we signed out of the amateurs, Vasyl Lomachenko, has become a big star.

Ramírez suffered a shock split decision defeat in which he was knocked down by a left hook inside the first minute of the opening round.

Ramírez dominated his opponent throughout the bout and, in the final round, landed a body shot which forced Ibarra to take a knee in a neutral corner.

Ramírez secured victory in the sixth round after trapping his opponent against the ropes and unloading a barrage of unanswered punches which forced the referee to end the bout.

[15][16] On 9 October 2021, Ramírez fought on the undercard of Tyson Fury vs. Deontay Wilder III, in a bout against Orlando Gonzalez Ruiz.

Ramírez started pressuring his opponent in the third round and eventually hit Donovan with a hard left hook which put him against the ropes.

Ramírez was booked to face the former WBO Junior-featherweight champion Isaac Dogboe on 1 April 2023, in the headliner of an ESPN+ broadcast event, which took place in Tulsa, Oklahoma.

[25] Ramirez made the first defense of his WBO featherweight title against Satoshi Shimizu on 25 July 2023, on the undercard of Naoya Inoue vs. Stephen Fulton.

Ramirez dominated and stopped Shimuzu in the 5th round, dropping him once before finishing him off with a flurry of unanswered punches and the referee called off the bout.

[27] Ramírez was scheduled to face Brandon Leon Benitez in a 10-round featherweight bout at James L. Knight Center in Miami, FL on June 29, 2024.

[29][30] Ramírez is scheduled to challenge Rafael Espinoza for WBO featherweight title in a championship rematch at Footprint Center in Phoenix, AZ on December 7, 2024.