The film also stars Ice Cube, Oscar-winning composer Common and Cedric the Entertainer.
Cole, 43, will play Dante, a fixture at the shop who shares his pithy comments on any subject under the sun, even though his cultural references are a few years out of date, reported Deadline.
Cole's casting comes a day after Common secured a role in the film.
Malcolm D Lee is helming "Barbershop 3". The script is by Kenya Barris and Tracy Oliver. The film does not have a release date.
The original film was released in 2002 and it was followed by the second part in 2004.