Michael started his career as a songwriter already at high school. In the early 1970s he became one of the best-known songwriters of Germany, which is the third biggest record-market in the world. He soon wrote songs for international artists, such as Charles Aznavour, Caterina Valente, Julio Iglesias, Nana Mouskouri, Herbie Mann, Lulu, Gilbert Bécaud, Dalia Lavi, Sister Sledge and many more. Among his collaborators as composers stand out Udo Jürgens, Vangelis, Jeff Barry, Karel Svoboda, Giorgio Moroder, and Leonard Cohen.

Unhappy with the productions of his songs, Michael started to record them himself. At first his productions dominated the charts of Germany, Austria, and Switzerland. In 1974 he became one of the creators of disco music and hit the top of both the Billboard and Cashbox charts in the US and other countries around the globe. His studio group, Silver Convention, represented by composer Sylvester Levay and Michael Kunze himself, was the first German aggregation to win the coveted Grammy Award. Based on this spectacular success – after Fly, Robin, Fly came such hits as Lady Bump and Get up and Boogie – Michael produced albums with a vast and varied array of internationally known performers.

In the 1980’s Andrew Lloyd-Webber asked Michael to translate his musical Evita into German. The success of his adaptation opened the doors of the German-speaking market for the modern Anglo-American musical. Michael’s reputation is in making the translated shows sound as if they were the original. Consequently, most of the West End and Broadway hit shows of the 1980’s and 1990’s were adapted by him, among them Cats, The Phantom of the Opera, A Chorus Line, Little Shop of Horrors, Sunset Boulevard, Company, Into the Woods and many others.

During the production of Evita in Vienna, Michael became a friend of Harold Prince. The legendary Broadway director encouraged him to write his own shows and helped him understand the craft of structuring a musical stage show. In September 1992 Michael’s musical Elisabeth with a score by Sylvester Levay opened in Vienna and became a smash hit that ran for six years. Most of the other shows Michael created with Sylvester and other composers became international successes, among them Dance of the Vampires, Mozart!, Rebecca  and Marie Antoinette. He is the first German librettist who was performed on Broadway. Currently his shows are running in 14 different countries.