Around 200 people gathered for the impromptu memorial at St James' Park, where flowers, football shirts and scarves have been left in memory of John Alder, 63, and Liam Sweeney 28.
The service outside the ground included a poem to the fans and ended with a minute's applause.
The pair were flying to New Zealand to watch the Magpies play a series of pre-season friendlies, but their flight from Amsterdam to Kuala Lumpur came down in eastern Ukraine on Thursday afternoon, killing them and 296 others.
Before the service Mr Sweeney's father Barry said: "This is one of the most amazing scenes I have ever seen. He and John I hope are in the sky, watching this. They would be amazed."
Mr Sweeney, a father of seven who cares for his terminally-ill wife Lesley, said: "I loved him to bits. He was a diamond."
Well-wishers gathered to pay their respects to the dead men, many of them leaving bouquets of flowers with a message to the two well-known fans who rarely missed a match.
Mr Sweeney was overwhelmed by the scale of the turn-out and thanked everyone for coming.
A fundraising initiative by Sunderland fans has reached £24,500, when the original aim was to get to just £100 and the surplus will be split by the Macmillan Cancer Support and the Sir Bobby Robson Foundation.
Liz Luff, of Sir Bobby's cancer-fighting charity, said: "The atmosphere was incredibly emotional. I've not experienced anything like it.
"It is a wonderful way to remember the pair and it has been very special."
Sir Bobby's widow, Lady Elsie, said: "Like everyone, I was shocked and upset when I heard about flight MH17 and the awful loss of life.
"I can't begin to understand what John and Liam's family and friends are going through. It's so hard to comprehend something as terrible as this.
"You often see the best of people in the worst of times and that's certainly true of the Sunderland fans who organised this collection in tribute to John and Liam.
"They, and everyone who has donated to it, are a credit to football and to the North East."