World number two Daniil Medvedev beat Marin Cilic to lead the Russian Tennis Federation to a third Davis Cup title.
Andrey Rublev had won the first singles match against Borna Gojo 6-4 7-6 (7-5) to put the Russians ahead in Madrid.
Medvedev did not drop a set at the tournament in a year where he won his maiden Grand Slam title at the US Open.
The Russians are the fourth nation to win both the Davis Cup and Billie Jean King Cup - the women's equivalent team competition - in the same year.
Medvedev was initially tested in the first set by 2014 US Open champion Cilic, who was part of the winning Croatian team in 2018.
The 33-year-old Croat built up a 4-2 lead in the first-set tie-break, but his forehand lost its way in the closing stages as Medvedev steadied his own nerves.
Cilic's serve deserted him in the early part of the second set, with Medvedev going an early break up and keeping that advantage.
"It feels amazing but I am more happy for the team than for myself," the 25-year-old said in his on-court interview.
"It is never easy to come at the end of the season but it was the best two weeks of my career."
Medvedev was also part of the team who won the ATP Cup at the start of the season.
Russians live up to pre-tournament favourite tag
World number five Rublev, 24, lost just two points on his serve in the first set against Gojo, 22, ranked 274 places below him.
The second set was more competitive and Rublev's early tie-break lead was narrowed before he closed out a 6-4 7-6 (7-5) victory.
The Russians, playing under the name of their federation because the nation is banned from international competition for doping violations, claimed their first title since 2006.
They were the pre-tournament favourites and have demonstrated why with some strong performances
Both Rublev and Medvedev were pivotal members of the team, with Rublev winning four out of his five matches, losing only to Spain's Feliciano Lopez in the group stages.
However, it was a muted celebration and a slightly less combative on-court interview after Medvedev previously baited the home crowd when he reminded the Spanish crowd on Saturday that his team had eliminated Spain in the group stage.