Poul Petersen started his career as an attacker, and was one of legendary centre forward Carl "Skoma'r" Hansen's best students. Petersen was a quick player, with great technique and a fierce shot. He made his senior debut for Akademisk Boldklub (AB) in the inside forward position, but eventually settled in the defense as a full-back. He was expected to hoof the ball away whenever he had stripped an opposition player of the ball, but instead he did smart dribbles and passes, and received some criticism for his adventurous style.
Poul Petersen made his debut for the Danish national team in June 1946, and quickly established himself in the starting line-up. In 1947, Petersen was selected for the Europe XI team, which played an exhibition game against the Great Britain national football team, losing 1-6 at Hampden Park. This game earned him the nickname "Europa-Poul". In the run-up to the 1948 Summer Olympics, Petersen suffered an injury. He was a part of the Danish team at the tournament, but despite declaring himself fit to play, he was left out of the starting line-up for the entire competition. Denmark won bronze medals at the tournament, but while most of the Danish players went on to sign professional contracts with foreign teams, Poul Petersen stayed in Denmark. He was a part of the Danish team which competed at the 1952 Summer Olympics in Helsinki. Denmark was eliminated in the quarter-finals by the Yugoslavia national football team, in what was Poul Petersen's last international game.