Medina dropped Ward twice in the second round to finish the job early and move to 19-3-2. For his part, Ward lost for the fifth time in his career and drops to 25-5-1.
Also on the bill, welterweight Glen Foot recovered from a recent reverse to Akeem Brown with a four round points win over Nathan Hardy.
Foot moves on to face Josh Leather on November 11 in Newcastle.
In Sweden, Anthony Yigit remained undefeated by seeing off a challenge from Sandor Martin.
Southpaw Yigit was given the verdict unanimously across the card and pushes to 21-0-1.
Elsewhere in Mexico, WBC flyweight title champion Jessica Chavez defeated Esmeralda Moreno on points to keep a firm grip on her green and gold strap.
Moreno hit the canvas in the seventh round as Chavez cruised to a 99-91 (twice), 99-90 triumph with the judges.
On the undercard, Felipe Orucuta stopped Edgar Jimenez in five rounds at the bantamweight limit.
Other Results:
10 – super featherweight
Dardan Zenunaj 14-3 TKO3
Recky Dulay 10-3
10 – super lightweight
Juan Jose Velasco 17-0 TKO9
Juan Garcia Mendez 19-3-2
8 – super bantamweight
Jose Osorio 9-3-1 SD
Roman Reynoso 20-2-2
