The groundbreaking competition will be shown live on Sky Sports in association with Matchroom Boxing, and on ESPN+ in association with Top Rank, and has gripped the imagination of the public.
WBO no. 11 and WBO Latino champion Castillo (20-2-1, 15 KOs) is now the sixth fighter to be confirmed to be taking part at 175 lbs, joining some of the best stars from around the world.
Castillo was an elite amateur, winning multiple titles and also competing at the 2008 Olympics in Beijing. Since entering the paid ranks he has displayed fantastic power, with 15 of his 20 wins coming by knockout.
Along with being the WBO Latino champion, Castillo has won the WBO NABO title as a professional too, and has also fought former interim WBA world champion Marcus Browne, with Castillo knocking Browne down during that fight in 2018.
He said: “I’m delighted to be entering the prestigious Golden Contract tournament. I’ll be chasing the knockout bonuses too and I’m definitely going to be the last man standing at light-heavyweight.”
Castillo joins a fantastic line-up at light-heavyweight, which includes former British champion Hosea Burton, unbeaten WBO European champion and WBO no. 12 Steven Ward and ex-British and Commonwealth light-heavyweight champion Bob Ajisafe.
Also part of the tournament are former English light-heavyweight champion Liam Conroy, and former WBC International champion Serge Michel.
The winner of each tournament will land a two-year, five-fight deal with a major promoter that guarantees six-figure purses for every fight along with global exposure.
To add to the excitement, fighters will not know their opponents until fight week, at the start of which the highly anticipated draws will be made. All titles held will be on the line in each fight and knockout bonuses are also on offer.
Three quarter-finals nights will take place before the end of the year, with three semi-finals nights scheduled for February / March and the all-important finals will be staged in May / June.