The 26-year-old, who suffered a devastating spinal cord injury in 2014, had always dreamed of being a father.
McKinnon and his wife Teigan welcomed their bundle of joy - named Harriet Anne - on October 7.
The couple posted a photo of their new little family to Instagram, both parents beaming with their daughter.
The happy news comes four years after McKinnon was left a quadriplegic while playing for the Newcastle Knights.
The couple also welcomed their firstborn on their one-year wedding anniversary.