The American Idol star split from 19 Management in August 2011 but remained signed to the recording arm of 19 Entertainment until now.
Lambert's contract expired in January and he decided to leave as part of his "evolution", but remains on the RCA Records roster.
"It's good for both sides. Adam can move forward with his plans and 19 isn't stuck in the middle," a source told The Hollywood Reporter.
A rep for Lambert added that the two parties have split "amicably and with the utmost respect for each other". He will still be managed by Direct Management Group, which is also home to Katy Perry.
There are plans for Lambert to tour Japan, Southeast Asia and Europe in 2013 and discussions about the direction of his third studio album have already started with RCA.
Watch Adam Lambert's video for 'Never Close Our Eyes' below: