Alonso is replacing retiring four-times champion Sebastian Vettel (35) at Aston Martin after a two-year stint with Renault-owned Alpine, who brought him back to the grid in 2021 after two seasons out.
"100%," the Spaniard told reporters when asked if he thought Mercedes-powered Aston Martin could turn things around after finishing behind the French team this year and last.
"Aston Martin are not here to finish fifth, or sixth, or fourth in the constructors' championship.
"They are here to win the world championship and that's what we'll be trying to do in 2023 and 2024," he said ahead of the Sao Paulo Grand Prix.
The double world champion signed a multi-year contract with the Silverstone-based team in August.
With two races to go, Aston Martin are battling Alfa Romeo, Haas and AlphaTauri for sixth in the 10-team constructors' championship, while Alpine are fighting to stay ahead of McLaren in fourth.
Alonso said for Alpine to beat McLaren it was a case of "seeing the chequered flag" - something that has not happened to him as often as he would like with five retirements including the last race in Mexico.
Even so, he said he was happy with his two years at the French manufacturer - who as Renault took him to his two world titles in 2005 and 2006 - and very grateful for the chance they gave him to return to Formula One.
Alonso has previously said he felt more wanted by Aston Martin than by his current employers.
