Chambers was outstanding for Arsenal in the Emirates Cup on the weekend.
"I saw him for the first time against us as a right back and I liked him," Wenger said.
"At the end of the season he didn't play too much at Southampton. But I made my mind up to buy him after I saw him against us."
Wenger added: "He's 19 years old and he came here without talking, he plays two good games and is not phased by the quality of the games and the opponents at his first time at the Emirates at 19.
"He's one of the satisfactions of the weekend."
For the big stories and the banter follow us on Twitter: @tribalfootball