During the filming of the 1951 film, Across the Wide Missouri, Montalbán was thrown from his horse, knocked unconscious, and trampled by another horse, resulting in a painful back injury that never healed. The pain increased as he aged, and in 1993, Montalbán underwent 9½ hours of spinal surgery which left him paralyzed below the waist and using a wheelchair. Despite constant pain, the actor persevered; he performed and provided voices for animated films and supported Nosotros. Filmmaker Robert Rodriguez created a role for him as "Grandfather Cortez" in the popular 2000s Spy Kids film series, and wrote the part specifically including his wheelchair – now jet-propelled to allow him to move throughout the scenes.
He married Georgiana Young (née Georgiana Paula Belzer; September 10, 1924—November 13, 2007), who had a brief acting and modeling career, in 1944; they had four children: Laura, Mark, Anita and Victor. Georgiana was the half-sister of the actresses Sally Blane, Polly Ann Young, and movie and television star Loretta Young, who nicknamed her "Georgie." After sixty-three years of marriage, she died at the age of 83, on November 13, 2007, predeceasing her husband by fourteen months.
Montalbán died on January 14, 2009 at his home in the Greater Los Angeles Area, at age 88. According to his son-in-law Gilbert Smith, Montalbán died of "complications from advancing age". His cause of death was later revealed to be congestive heart failure. He is buried next to his wife in Culver City's Holy Cross Cemetery.