In 1991, Irwin met Terri Raines, an American naturalist from Eugene, Oregon, who was visiting wildlife rehabilitation facilities in Australia and had decided to visit the zoo. According to the couple, it was love at first sight. Terri said at the time, "I thought there was no one like this anywhere in the world. He sounded like an environmental Tarzan, a larger-than-life superhero guy." They were engaged four months later and were married in Eugene on 4 June 1992. Together they had two children: a daughter, Bindi Sue Irwin, and a son, Robert Clarence "Bob". Bindi Sue is jointly named after two of Steve Irwin's favourite animals: Bindi, a saltwater crocodile, and Sui, a Staffordshire Bull Terrier.
Irwin was as enthusiastic about his family as he was about his work. He once described his daughter Bindi as "the reason [he] was put on the Earth." His wife once said, "The only thing that could ever keep him away from the animals he loves are the people he loves even more." Although the Irwins were happily married, they did not wear wedding rings; they believed that in their line of work, wearing jewellery could pose a hazard to them and/or the animals. Steve and Terri spent their honeymoon trapping crocodiles together. Film footage of their honeymoon, taken by John Stainton, became the first episode of The Crocodile Hunter.