Arteta, who played 141 matches with Cahill, explained that he spoke to the Socceroos legend about Ryan's character prior to completing the deal.
"I did speak to him obviously because I always like to have information with players, with coaches that have spent time with them," Arteta said in a press conference.
"I got really positive feedback from Tim as well as other people. When you have reliable sources, you feel much more confident to make any decision."
Ryan is yet to play for Arsenal since joining the London giants last week, however, Arteta is impressed by what he sees in training.
"He's settled really quickly. I was really impressed when I talked to him.
"He's really focused, really engaged with what we want to do. He's a very professional guy and he's coming here to compete with Alex (Runarsson) and with Bernd (Leno).
"That's the mentality and the desire that we want for any player that joins our club."
Ryan has been on the bench for the first two games and is unlikely to start ahead of Bernd Leno in the Premier League unless Leno suffers an injury or a significant drop in form.
However, Ryan could be in line to start his first match for Arsenal when they take on Benfica on February 19 in the Europa League.
