On the penultimate day of the trade period, the Swans offloaded Blakey, draft pick No.52 and their 2028 second-round selection in exchange for a glut of picks.
The Kangaroos shipped picks No.6 and No.47, a 2027 second-round pick, a 2028 first-round selection and a 2028 second-round pick to get the deal done on Tuesday.
Blakey had five years remaining on his Swans deal, but requested a trade following a fracturing of his relationship with the club.
He was one of five Sydney players who served a club-imposed ban through the AFL finals for breaching the Swans' behavioural standards at the Pullman Hotel in East Melbourne.
The players' punishment was separate to an ongoing Victoria Police investigation into an alleged sexual assault at the hotel.
No charges have been laid, and AAP is not suggesting any wrongdoing.
In a statement issued by North Melbourne, the 26-year-old offered an apology.
"I want to say that I'm sorry for the events that led up to my exit from Sydney," Blakey said.
"I know I have to win back the trust of the broader community, football and otherwise.
"Now I have the opportunity to move forward and I want to thank North Melbourne for helping me find a fresh start."
The dashing half-back met with Geelong, St Kilda and Gold Coast, but had his head turned by North's reported eight-year offer worth more than $11 million.
Blakey played 173 games for Sydney after arriving at the Swans as an academy product with pick No.10 in the 2018 draft.
He was also eligible to join North Melbourne or Brisbane as a father-son selection through his dad John, who played 224 games for the Kangaroos, including their 1996 and 1999 premierships.
After Blakey's mega move, the Kangaroos completed a trade to send former No.4 pick Zane Duursma to Melbourne.
The 21-year-old forward was traded to the Demons along with pick No.52 in this year's draft for picks No.33 and No.49.
North will now turn their focus back to bringing Nick Murray to Arden Street after the young Adelaide defender requested a trade.
As the trade deadline approaches, deals are yet to be orchestrated for Keidean Coleman, Lachie Whitfield, Jayden Short, Jack Viney and Trent Rivers.
Essendon are working on a trade for Brisbane's Coleman after the fringe Lion requested a trade to the Bombers.
Coleman starred in Brisbane's four-point grand final loss to Collingwood in 2023, finishing second in Norm Smith Medal voting behind Bobby Hill.
The 26-year-old has since managed just 15 senior games, suffering a season-ending ACL injury in the first round of 2024 and then soreness and a quad injury following his return in 2025.
In that span, Coleman fell behind Darcy Wilmot and Jaspa Fletcher in the Lions' half-back pecking order and missed all three of Brisbane's flags.
One of three Essendon draft picks (17, 21 and 27) is expected to form the crux of any deal.
GWS and Carlton remain in a staring contest over Whitfield, with the Giants asking for a first-round pick in exchange for the 32-year-old.
West Coast are hopeful of brokering a deal or deals with Melbourne for former captain Viney and defender Rivers.
Also on Tuesday, Collingwood secured ruck cover after trading a 2028 third-round pick for youngster Flynn Riley.
Collingwood list boss Justin Leppitsch reiterated no club had contacted him to discuss defender Dan Houston, and said a deal for Richmond's Short was unlikely.
The trade period closes on Wednesday night.
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