During his pro club career, Castrillón played in the Uruguayan League, with Club Malvín (1992–1996), Cordón (1997–1998), and with Defensor Sporting, from 1999, until his retirement in 2014. He won the Uruguayan League championship in 2003 (two tournaments), and in 2010, winning all three titles with Defensor Sporting. He was also an Uruguayan League runner-up in 1997 and 1998, with Cordón, losing both times against Welcome. He was also an Uruguayan League runner-up with Defensor Sporting in 2009, losing against Biguá, in 2013, losing against Aguada, and in 2014, losing against Club Malvín.
Castrillón was a member of Uruguay's junior national teams. He played with their Under-16 junior national team in 1991, and with their Under-22 junior national team in 1996.
In 2010, Castrillón started coaching the juniors youth team of Defensor Sporting. First with their Under-13 team, from 2010 until 2012. In 2013, he coached their Under-15 team, and in 2014, he began coaching their Under-18 and Under-20 teams.
In 2015, he coached Club Nacional in the Uruguayan Second Division. In August 2018, he started coaching Club Atlético Peñarol, in the Uruguayan Third Division.
His team, Club Atlético Peñarol won the title with a record of 15-0, finished unbeaten.
In June 2019, he started the Uruguayan Second Division with Club Atlético Peñarol, until he finished as Peñarol's coach on 24 August 2019, when in the Uruguayan Second Division his team lost against Unión Atlética with a result of 78-73.