The 40-10 victory gives the Roosters' hopes of playing NRL finals football a big boost, while Melbourne's loss means Canberra will be presented with the JJ Giltinan Shield as minor premiers at their clash with Wests Tigers on Saturday.
The Storm were looking to mark Bellamy's 600th match as their coach in style but the celebrations fell flat in their Friday night clash as the Roosters overcame a 10-0 halftime deficit, piling on 40 unanswered points, Melbourne's worst second-half in the club history.
Bellamy had to be convinced to go on stage post-match to be presented with an award by NRL boss Andrew Abdo.
The undermanned hosts were swamped by a rousing Roosters, with rugby convert Nawaqanitawase crossing four times to take over the lead as the NRL's top try-scorer, scoring 20 for the season.
While the result didn't impact the Storm's top-two ladder position, which is locked in, the eighth-placed Roosters moved four points clear of the chasing Dolphins and Manly.
The Dolphins face Gold Coast on Sunday while the Sea Eagles are away to St George Illawarra on Saturday to keep their very slim chance of a top-eight berth alive.
Bellamy lambasted his team's second-half defence, describing it "as soft as butter".
"It certainly wasn't the result we wanted, but the lack of effort was the thing that stood out for me," he said.
"We were ... I can think of a couple of words but I probably can't say them ... but 40-0 in a half of footy, that's embarrassing - that's about the nicest word I could use."
The Roosters were under pressure in the build-up after being embroiled in South Sydney hooker Brandon Smith's police investigation while the odds were against them, only winning four of 14 matches in Storm territory.
The Storm kept a frustrated Roosters outfit tryless in the first half through some desperate defence while the visitors did themselves no favours with seven penalties.
But the visitors reined in that ill-discipline and got their attack firing, thanks to skipper James Tedesco and Nawaqanitawase, who stood up Storm centre Grant Anderson to cross for this fourth.
With stars Xavier Coates, Nick Meaney, Eli Katoa and Josh King rested and skipper Harry Grant suspended, Melbourne completely fell away in the second half.
After the flying winger scored three in a row, Roosters centre Robert Toia and then Tedesco got in on the try-scoring action.
Their coach Trent Robinson said it was "pleasing" to see his side perform when it counted.
"Still a long way to go but we're on the right track there," he said.
"I'm really proud of the guys ... but there's always next week."
He said that former Wallabies gun Nawaqanitawase was on the path to being a superstar.
"There's a high intelligence, his carries out of the backfield, his finishing in the tries, there's some smarts in and around how he looks after the ball and how he knows his position on the field and the position of his feet.Â
"There's a lot of little things there that are incredibly impressive. So I'd say he's on a good path."
Melbourne's misery was compounded with Nelson Asofa-Solomona put on report for a high shot on Nawaqanitawase, with the prop playing his first NRL game since a two-match ban.
