Kroos played a key role as Real Madrid beat Borussia Dortmund 2-0 at Wembley.
The German, along with teammates Dani Carvajal, Nacho and Luka Modric joined Madrid legend Paco Gento as the most decorated players in European Cup history.
Real boss Carlo Ancelotti said his door remains open should the 34-year-old have a change of heart after announcing the shock decision last month that he will retire after representing his country on home soil at Euro 2024.
The normally unflappable Kroos had a rare emotive outburst as he punched the air and pointed to the Madrid club crest when he was replaced by his long-time comrade Modric with just a few minutes remaining at Wembley.
"He’s finished at the top. It is not possible to go out better," said Ancelotti.
"He is a legend of this club and obviously we all thank him for what he has done.
"Not just in his play but his attitude, his professionalism. He never missed a day in these 10 years. We hope he changes his mind, we are here if he does."
Kroos' Champions League haul ended where it began, by beating Dortmund at Wembley.
He was a Bayern Munich player when they won the competition at the home of English football in 2013, although injury prevented him from featuring in the final.
'I'll miss this'
Fresh from helping Germany to win the World Cup in Brazil, Kroos then joined Madrid in 2014 and has become part of a generation that has marked a second era of European domination for the Spanish giants.
Gento was part of the Madrid side that won the first five European Cups from 1955 to 1960.
Real have won six Champions Leagues in the past 11 seasons, with Kroos featuring in five of those triumphs.
"I'll miss this," said Kroos. "Of course I wanted to say goodbye with this Champions League victory.
"The title means an unbelievable amount to me."
Unsurprisingly, he was at the heart of the action as Madrid wrestled control away from Dortmund after a dreadful first half from Ancelotti's men.
Madrid were fortunate not to trail at half-time as Karim Adeyemi and Niclas Fuellkrug missed big chances for Dortmund.
"The first half really wasn’t good from us," added Kroos. "Then we got into the game better and scored the goal. We were fully there and the better team, but it took a long time until we were the better team tonight."
Kroos began the turn the screw as he completed the most passes and had the most touches of anyone on the Wembley turf.
A trademark free-kick that was destined for the top corner was turned away by Gregor Kobel to deny him a goodbye goal.
But he still had a decisive part to play as it was from Kroos' corner that Carvajal rose highest to power home the crucial opening goal.
Vinicius Junior quickly added a second to get the Madrid party started and allow Kroos a standing ovation from the travelling thousands from Spain.
More glory could be to come in his swansong after he ends his international exile to return for Germany at Euro 2024.
Kroos, who had stepped down from international duty after Germany's last-16 Euros exit to England in 2021, has answered the call from manager Julian Nagelsmann to return for one last major tournament.
But he has fulfilled his ambition to bow out on his own terms at the top of the game at club level.