The French striker was in talks with the South Wales club over the course of the weekend and a permanent deal for the 24-year-old has now officially been completed.
Ngog joined Bolton from Liverpool in January 2011. He made a total of 91 appearances for Wanderers in all competitions, scoring 16 goals.
Bolton Wanderers would like to thank David for his contributions during his time at the club and wish him well for the future.