The fly-half, who was below his best against Wales and France, was outstandng as Scotland beat England for the first time in a decade.
Huw Jones scored two tries and Sean Maitland dotted down the other in a rampant first-half display for the hosts.
Owen Farrell threatened to spark an England revival when he scored after the break but Scotland defended their line heroically to secure the win.
"It is hard to fit into words, at the end of the game I did not know how to feel. It is an immense thing experience to win the Calcutta Cup for the first time in ten years," he said.
"I have not stopped smiling. It means so much to the crowd and it means so much to us too."
It says a lot about Russell's performance that he beat match-winner Jones to the man of the match award.
The fly-half was creative throughout with ball in hand and solid in defence as England pushed for a route back into the game.
His standout moment was on the half-hour when his audacious wide pass to Jones put the centre away, and a few phases later, Maitland was over.
Russell was perhaps Scotland's best player in their superb autumn, where they beat Australia and pushed world champions New Zealand so close.
And head coach Gregor Townsend hailed the Glasgow Warriors playmaker, who timed his return to form at exactly the right time.
"Finn was outstanding for us in November and taking on the best teams in the world in New Zealand and Australia he was world class," he said.
"He hasn't had the best of starts but the second half against France was very good and today he played like he did in November.
"The pleasing thing was seeing Finn play the rugby we know he can play, putting passes in space, tackling very very well.
"I thought he was outstanding in defence, making good decisions on kicking and when to run.
"There was a real balance to his game and he was creating a lot of space for us in the way he was playing and engaging with the forwards, and I think he can kick on from here.
"Every player is going to go through a period where they're not got into the game as quickly as they want to, so he was well prepared, trained very well through the week, had a very good focus today and played very well."