Negotiations were under way for a live television broadcast from the Australia Zoo's 5,500-seat auditorium, known as the "Crocoseum," Irwin's wife, Terri, announced Wednesday.
Free tickets will be distributed for the public service, said Peter Lang, a spokesman for the zoo, and there are plans to set up screens for broadcasts to venues in the Queensland state capital, Brisbane, and the nearby Sunshine Coast.
Irwin was fatally wounded by a stingray last week as he recorded a television show on the Great Barrier Reef.
His wife, Terri, and 8-year-old daughter, Bindi, are to speak at the memorial service, along with Irwin's father, Bob, and his close friend and manager, John Stainton, the family said in a statement.
Stainton said last week the service would be a "celebration of his life, not a sad funeral — Steve would not have wanted us to have everyone around crying."
Irwin's family and closest friends held a private funeral Saturday, telling stories around a campfire on the grounds of the zoo, the entertainer's base in eastern Queensland.
Bob Irwin has said the family turned down an offer of a state funeral because his son would not have wanted it. The father said Irwin would, however, have liked a public service for his fans to celebrate his life.
Although larger venues for the public event had been suggested, Terri Irwin said her husband would have wanted the service held at the Crocoseum.
"I cannot see how a memorial service would work in any other place other than the Crocoseum, which he built here at the zoo and of which he was so proud," she said in a statement. "I would therefore ask that everyone please bear with me in this wish and help me to make this happen."
Terri Irwin, originally of Eugene, Ore., thanked her husband's fans for their kindness and support following the death of her "soul mate."
"I would like to thank everyone for the overwhelming outpouring of love, support and prayers for my family," she said in her first public comments since Irwin's death.
Thousands of fans have flocked to the 60-acre zoo to lay flowers, candles, cards, stuffed animals and messages of support scrawled on Irwin's trademark khaki shirts.