The 22-year Spanish right-back completed his move from Marseille to the Premier League club on Friday, and Di Matteo is pleased with his new signing.
"He is a young player from Marseille, who has come through all the ranks with the youth level of the Spanish team, and he will give us cover at the right-back position with Paulo Ferreira and Branislav Ivanovic," he is quoted as saying on Chelsea's official website.
"It gives us more options for the future and competition. We will see who is going to be playing."
Azpilicueta joined his new Chelsea teammates for training on Friday.