Froome (Sky) had virtually secured victory with a solid performance in the difficult climb up the Alto de l'Angliru on Saturday, which marked the last competitive stage of the three-week race.
Matteo Trentin (Quick-Step Floors) once again displayed his raw power on the final 117.6km stage of La Vuelta 2017, winning the bunch sprint to claim a fourth win, this time ahead of Lorrenzo Manzin (FDJ) and Soren Kragh Andersen (Team Sunweb).
“The job started from when we entered the circuit to the finish and we could gain another victory," Trentin said.
"(Chris) Froome told me he wanted to defend the green jersey. It's a pity (not to get the green jersey) after four victories. I won two bunch sprints and two hard days and I can be happy with it”
Froome, who earlier this year clinched his fourth Tour de France title, had finished runner-up in La Vuelta three times, including last year.
He became the third man to complete the Tour-Vuelta double in the same season, after Jacques Anquetil in 1963 and Bernard Hinault in 1978, when the Vuelta was still held in the spring before the Tour.
"I've been fighting for this victory now for six years and three years I've been standing on the second step. It's just amazing to stand on the top step this time,” Froome said.
"Today in the final I figured this would probably be the only time in my life to try and win the green jersey of a Grand Tour, so I gave it everything I had and managed to get a few points at the finish there.
“Obviously I couldn't be happier with the result. I'm just a biker racer and of course if there's a competition to be won I'm going to go for it."
Alberto Contador came in seven seconds behind in the final professional stage of his career a day after winning the punishing last mountain stage at the Alto de l'Angliru to bow out in style.
The three-time Vuelta winner was serenaded by Spanish supporters on the podium by the Cibeles palace in Madrid, while his Trek-Segafredo team mates jokingly urged him to postpone his imminent retirement, chanting "One more year for Alberto".
“I don't have words to explain the feeling I had in that moment. To cross the finish alone in front of my home public,” Contador said.
“It's a dream. I don't know a goodbye better than this. Now is the moment to stop. When I started as a professional, I said I wanted to finish at the top level. And I think that now is the perfect moment for this. I can only say ‘thanks, thanks and thanks'.
“I gave the maximum, 100 per cent in the race. In the last 15 years, I did everything with my heart. It's important. Cycling is a sport where the most important is the victory but I also think the spectacle is important. I did everything I could during La Vuelta. And I thank Trek-Segafredo for giving me this opportunity to attack when I want.”