ODA chairman John Armitt told NCE that the change, along with three others, will save £70M.
Fencing, which was to be held in a temporary venue on the Olympic Park, will move into ExCeL London – already an Olympic venue for Boxing, Judo, Table Tennis, Taekwondo, Weightlifting and Wrestling, and for Paralympic Boccia, Table Tennis, Power-Lifting and Wheelchair Basketball.
London 2012 chairman Sebastian Coe said: "We only want to build what can be used to maximum effect after the Games – and the IOC has recognised our desire to focus on a tangible legacy and approved these changes today.”
The ODA has also made changes to three other venues around the site.
The Handball Arena will be shrunk and the finals moved to the 12,000 seat Basketball venue. The ODA said the venue has been "re-oriented to make sure it leaves a strong post-Games legacy".
The temporary venue for Basketball will move from the southern end of the park to the northern end of the park.
The BMX venue will move a small distance and now be adjacent to the Velodrome. This puts the venue in its final legacy position, with no need to take it down and rebuild it after the Games.
“We have always said that our intention was to build truly sustainable venues which will provide a strong elite and community use legacy for sport for generations to come, long after the final race has been run in 2012," said Coe.
"These small changes to our temporary venue locations in the Park are designed to maximise the sporting legacy we leave behind – as well as optimise the Games time experience for athletes and spectators."