Henry Field had the time of his life when he met Knights and Panthers stars and did the coin toss before last Sunday's match.
The Mark Hughes Foundation set up the experience for the five-year-old and his family for the Beanies for Brain Cancer round.
Henry was diagnosed with brain cancer in June last year and is now in remission.
Mum Antoinette Field said it was a special day for Henry, his dad Jay and brothers Leo, 7, and Jack, 3, who all love rugby league.
"They got to experience the warm-up from the sidelines, which was really exciting. They're huge Panthers supporters," Mrs Field said.
"They're big Nathan Cleary fans. They got to meet him in the morning, which they loved.
"All the players from the Panthers and Knights were incredible with the boys. It was an experience they will never forget."
Mrs Field, of Box Hill, recognised the "hard work the Mark Hughes Foundation does for brain cancer research".
The foundation's co-founder Kirralee Hughes, Mark's wife, said "they're the most beautiful family".
Mrs Hughes said the foundation was delighted to "put a smile on their faces and make their day".
She said patients and their families can "feel so lonely" after a diagnosis.
"It makes them feel like they're part of a bigger community that's banding together," she said, of the foundation helping people.
"It's different people going through the same thing."
Brain cancer causes more deaths in children than any other type of cancer.
"We wanted to come to the Beanies for Brain Cancer round last year. Henry had just been diagnosed," Mrs Field said.
"So we planned to go but ended up in hospital for a month, so we couldn't.
"This was our first one, so we were excited to come. It made their [her boys] entire life."
Before he was diagnosed, Henry would "wear his rugby kit underneath his clothes all week in preparation for Saturday".
"He played rugby for the Redfield under 6s. He was two years younger than all the other kids, but wanted to get out there and play.
"He played the weekend before he was diagnosed and scored a try.
"We noticed something was a little bit off with him and knew he wasn't feeling well."
On the Monday, his teacher said "something's not right, you need to take him to ED now".
"That's how we found out," she said.
"After brain surgery, he couldn't talk or move. He's had to relearn how to do everything from scratch.
"He's been wheelchair-bound since he was diagnosed, but he's made huge strides and come really far."
Henry has had 30 radiation treatments and four cycles of chemotherapy.
"He's in remission now. He's doing amazing," she said.
