Valtteri survived the first lap contact to take a comfortable second behind Verstappen - his best ever result at the Autódromo Hermanos Rodríguez - and cut the gap to Vettel in P2 in the Drivers' Championship to 15 points with two rounds to go.
"The right man won the title this year, Lewis absolutely deserves this!" said Valtteri. "He's my team mate, so I know he's not only talented, but also a hard worker, and a really nice guy.
"Even though we're competing, I'm also happy for him - but I still want to beat him next year.
The race today was pretty straightforward after the start. I saw in Turn 2 that Max and Sebastian were side-by-side, and one of them went a bit wide, so I knew Turn 3 was going to be a mess.
"I decided to go inside and cut the corner and get a good exit. After that there was not much happening. Unfortunately, we couldn't challenge Max today, so I drove it home.
"We saw we didn't have the pace to win the race, so we have a lot of things to learn. But overall, it was not a bad day for us - I felt I got the most out of the car, it was good to be on the podium after such a long time, and of course Lewis won the title."