Lenin Castillo has four losses against four opponents on his boxing record. For a list of Castillo's best fights, refer to "Best fights of Lenin Castillo".
On September 25, 2021 Lenin Castillo faced off against Callum Smith in a light-heavyweight bout at age 33. He was coming in with a record of 21-4-1 (16), and Smith was 31 years old and with a record of 27-1 (19). Castillo lost the fight via 2nd-round KO.
On October 12, 2019 Lenin Castillo faced off against Dmitry Bivol at age 31. He was coming in with a record of 20-3-1 (15), and Bivol was 28 years old and with a record of 16-0 (11). Castillo lost the fight via 12-round unanimous decision.
On August 4, 2018 Lenin Castillo faced off against Marcus Browne at age 29. He was coming in with a record of 18-2-1 (13), and Browne was 27 years old and with a record of 21-0 (16). Castillo lost the fight via 10-round unanimous decision.
On February 10, 2017 Lenin Castillo faced off against Joseph Williams at age 28. He was coming in with a record of 15-1-1 (10). Castillo lost the fight via 8-round majority decision.