After Michigan lost in the West Regional Semi-finals of the 2007 NCAA Tournament, rather than return to Michigan and finish the semester, Johnson jumped to the NHL and signed his entry-level contract with the Kings in March 2007, making his NHL debut on March 29 against the Vancouver Canucks. He would play five games on the season, recording 18 penalty minutes and no points. Johnson recorded his first NHL point on October 10, 2007, assisting a Kyle Calder goal in a loss to the Dallas Stars. His first goal came on October 19, 2007, against goaltender Roberto Luongo of the Vancouver Canucks. Johnson scored three goals and eight assists that season.