The 27-year-old three-cap England stopper has penned a three-and-a-half year deal at Villa Park as boss Steven Gerrard bolstered his defence.
Chambers was out of contract at The Emirates Stadium this summer, with Villa paying an undisclosed fee for his services.
The former Southampton academy graduate made 122 appearances for Arsenal in almost eight years at the club with whom he won FA Cup and Community Shield medals.
He has also enjoyed loan spells at Middlesbrough, in 2016/17, and Fulham in 2018/19.
The sudden move arrived out of the blue but sees Gerrard add versatility to his ranks. Chambers can operate at centre-half or right-back, as well as in defensive midfield.
Chambers, who won all three of his international caps in 2014, has featured just five times for Arsenal's first team this season with just two Premier League starts, both coming in August.
He did feature as an early substitute in the Gunners' recent Carabao Cup semi-final first-leg draw at Liverpool.
Chambers is likely to provide cover and competition to right-back Matty Cash and Villa's central defensive options of Tyrone Mings, Ezri Konsa and Kortney Hause.