Sheffield's Brook, 28, beat Shawn Porter on points on Saturday and is set to defend his title for the first time at Sheffield Arena on 6 December.
Fellow British fighter Amir Khan has already said he would like to take on the undefeated champion. "I think you have to say Kell is now in the running to face Floyd Mayweather," Hearn told BBC Radio Sheffield.
"Everyone in the division wants to fight Floyd, but if you hold a world title then you are more likely to face him than if you don't.
"He's an obvious opponent and Mayweather is a target for 2015." Mayweather, 37, is unbeaten in 46 fights and is set to defend his World Boxing Council and World Boxing Association titles against Argentina's Marcos Maidana on 13 September. Hearn believes that any potential bout with the American would come after the Khan fight. The Bolton fighter had previously suggested that Brook would pull out of the bout with Porter as he 'did not think he could beat him'.
After his win in California Brook said a fight between himself and Khan was one that British boxing fans would want to see. "For me it is an outdoor event for spring or summer 2015," Hearn added. "It is the same sort of size as Carl Froch against George Groves and it would be good to see it at Wembley or Bramall Lane or Old Trafford. "I think talks will begin with Khan's camp possibly this week."