Porsgrunn is served by the Grenland Line railway with connections to Oslo (about two and a half hours), Skien, and other towns in the Grenland region. The nearest airport is Sandefjord Torp, about 40 kilometres southwest, which offers budget flights to European destinations. Oslo Airport is about two hours by car.
Local buses connect Porsgrunn with Skien and other Grenland municipalities. The E18 motorway passes nearby, making it easy to reach by car from Oslo or from the coast.