The first full title unification fight in the history of the 154-pound division was officially announced Thursday.

Premier Boxing Champions and Showtime revealed that champions Jermell Charlo and Brian Castano will fight for four 154-pound titles July 17. Showtime will televise Charlo-Castano, as BoxingScene.com reported Sunday, from a venue to be determined.

Their fight could take place in Houston, Charlo’s hometown. Wherever they meet, Charlo, 30, and Castano, 31, will fight for Charlo’s IBF, WBA and WBC belts and Castano’s WBO championship.

Their 12-round battle will be the second consecutive title unification fight for Charlo (34-1, 18 KOs).

The Houston native knocked down Jeison Rosario three times and stopped him with a body shot in the eighth round of Charlo’s last appearance, a Showtime Pay-Per-View main event September 26 at Mohegan Sun Arena in Uncasville, Connecticut. Charlo captured the IBF and WBA belts from the Dominican Republic’s Rosario (20-2-1, 14 KOs) and defended his WBC crown.

Charlo and his twin brother, Jermall Charlo, co-headlined Showtime’s pay-per-view show September 26. Jermall Charlo clearly out-boxed Ukraine’s Sergiy Derevyanchenko to win a 12-round unanimous decision and retain his WBC middleweight title.

Jermall Charlo’s next fight was announced Thursday as well. The heavier Charlo (31-0, 22 KOs) will headline a “Showtime Championship Boxing” broadcast June 19, when he’ll make an optional defense of his WBC belt against Mexico’s Juan Macias Montiel (22-4-2, 22 KOs) at a venue to be announced in Houston.

Castano (17-0-1, 12 KOs) became an obvious opponent for Jermell Charlo once he beat Brazil’s Patrick Teixeira (31-2, 22 KOs) by unanimous decision in their 12-round fight for Teixeira’s WBO junior middleweight title February 13 at Fantasy Springs Resort Casino in Indio, California. Argentina’s Castano, who was the mandatory challenger for Teixeira’s title, became a two-time 154-pound champion two months ago.

Castano previously held the WBA super welterweight title. The WBA stripped him in June 2019 because Castano declined to defend his title against mandatory challenger Michel Soro in France, Soro’s home country, due to financial concerns.

Castano defeated Soro by split decision in July 2017 to win the WBA interim super welterweight title. It took the promoters of that event in Evian-les-Bains, France, approximately 10 months to pay Castano his purse from that fight in installments, which was why he was hesitant to work with them again for a rematch against Soro (35-2-1, 24 KOs).

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.