The 34 year-old, who was facing an opponent weighing 182lbs on the night, employed a body attack game-plan from the off, although finished the fight with some superbly timed head shots.
Cotto won every round until a crushing left hook in the fourth put Geale down hard and ‘Junito’ then followed it up with another for good measure. Referee Harvey Dock asked Geale if he was okay upon getting to his feet for the second time, but the Australian said no and the contest was called off.
Puerto Rican legend Cotto now moves on to a massive clash with Canelo Alvarez in the fall and could be ready to relinquish the WBC 160lb belt that made him a four-weight title holder.
Admitting he was not a middleweight after the fight may have been the first step in Cotto making the move back to super welterweight for his impending pay-per-view meeting with Canelo.
In the co-feature, former world champion Wilfredo Vazquez Jr suffered a fifth career defeat and may need to re-evaluate his career at this point.
At one time a seemingly unbeatable super bantamweight ruler, Vazquez, 30, has seen his star fade considerably since 2011 and his latest loss to Fernando Vargas only compounds his misery.
Vargas was much the busier and more accurate of the two fighters over eight rounds and was rightly awarded a 79-73, 78-74 and 77-75 victory on the scorecards.
Earlier, light heavyweight Junior Younan stopped Mike Sawyer in two rounds, whilst Angel Luna ended the undefeated run of Jose ‘Wonder Boy’ Lopez.
Amateur star Dustin Fleischer moved to 2-0 with an early win against debutant Karim Miller and super bantamweight Shawn Simpson halted Damon Simon on his maiden pro bout.