Outgoing Formula 1 world champion Nico Rosberg has congratulated former Mercedes teammate and rival Lewis Hamilton on his fourth title win in Mexico on Sunday, say it was "well-deserved".

Rosberg retired after beating Hamilton to the F1 title at the end of the 2016 season in Abu Dhabi, and has since been a keen observer of his ex-teammate's fight with Ferrari's Sebastian Vettel while pursuing interests outside of the sport.

Hamilton clinched his fourth F1 world title by finishing ninth in Sunday's Mexican Grand Prix, with Rosberg sending his congratulations and reflecting on the season as a whole in a vlog on his YouTube channel.

"To begin with, Lewis, congrats. A really awesome performance this year and a really well-deserved fourth championship, very, very impressive of course," Rosberg said.

"I hope you all enjoyed the race today, I definitely did. What a season it has been also overall. The battle, Mercedes and Ferrari with Red Bull in the mix, perfect I think, and also then Lewis versus Seb has been exciting, and everyone else came in the mix from time to time.

"And then, of course, a big congrats to Mercedes because really incredible job what you've done across this massive regulation change having to completely start from scratch and then to again dominate like that, especially now towards the end of the season, I think that's very, very impressive."