Planck will be carried into space from the Guiana Space Centre, Kourou, French Guiana, in July 2008 by an Ariane-5 launcher. Planck will be launched together with ESA's Herschel spacecraft. The two vehicles will separate shortly after launch and proceed independently to different orbits about the second Lagrange point of the Earth-Sun system (L2).

The Ariane-5 launcher will burn its solid boosters for slightly less than 2½ minutes and its main and upper stage engines for about 25 minutes to inject Herschel and then Planck into transfer trajectories bound for L2. Upon separation, Planck will be spin stabilised.

After a journey lasting between four and six months, Planck will make a major manoeuvre to enter its operational orbit, a small Lissajous orbit around L2, 1.5 million kilometres away from the Earth.