Bohlen was still in school when he started writing music. In the late 1970s, he worked as a songwriter at the Hamburg-based label Intersong for numerous Schlager singers. In 1978, he founded the short-lived duo Monza with Holger Garbode. Their first single, "Hallo Taxi Nummer 10", written and produced by Tony Hendrik, was Bohlen's first record and was unsuccessful. Monza released a second single, "Heiße Nacht in der City", a German-language cover of Nick Gilder's "Hot Child in the City", which also was unsuccessful. In 1980, he began working for the Berlin-based label Hansa. That same year, under the pseudonym Steve Benson, he released a solo single in English, "Don't Throw My Love Away". It was followed in 1981 by two other singles under that name, "Love Takes Time" and "(You're A Devil With) Angel Blue Eyes". None of them reached the top 100, which led to the abandonment of the project in 1981. Soon after, he joined the band Sunday, with which he appeared on the "ZDF-Hitparade" in early 1982 with the song "Halé, hey Louise". The song was covered by artists such as Ricky King. In 1983, Bohlen wrote the song "Mit 17" for Bernd Clüver, which reached the third place of the German pre-selection for the Eurovision Song Contest.