Noakes' decision to leave the franchise follows that of rugby league convert Benji Marshall, who was released last week after his failure to adapt to the 15-man code.
"Chris is a very accomplished flyhalf," London Irish director of rugby Brian Smith said on the club's website. "He's a prolific goal kicker with a 75 percent average in the Super 15 and he knows how to get a backline moving.
"He is also eligible to play for England and we feel he is very well suited to the European game."
Noakes, who has signed a two-year deal with the Exiles, played for both the Highlanders and Blues in Super Rugby.
The 28-year-old had neck surgery last year and has played three games for the Blues this season, though suffered a heavy head knock against the Wellington Hurricanes and missed last week's game against New South Wales.
He was not considered for Auckland's match against Queensland on Saturday.
