Adolphus Frederick George Ernest Albert Edward of Mecklenburg was born in Neustrelitz, the third child and eldest son of Adolphus Frederick V, Grand Duke of Mecklenburg, and his wife, the former Princess Elisabeth of Anhalt. He attended a gymnasium school in Dresden and later studied jurisprudence in Munich and served in the Prussian army. Adolphus Frederick became heir apparent to the Grand Duchy, with the title of Hereditary Grand Duke of Mecklenburg-Strelitz, following the death of his grandfather Grand Duke Frederick William on 30 May 1904.

Adolphus Frederick and his younger brother Duke Karl Borwin are said to have agreed that Adolphus Frederick could devote his life to painting, while Karl Borwin would marry and continue the dynasty; but this agreement could never be realised, as Karl Borwin was killed during a duel with Count George Jametel in 1908. Adolphus Frederick was subsequently reported to be engaged to various European princesses, including Princess Viktoria Luise of Prussia, the only daughter of the German Emperor William II and his consort, Augusta Victoria of Schleswig-Holstein.

He succeeded as Grand Duke on the death of his father on 11 June 1914, just a few weeks before the outbreak of World War I. Adolphus Frederick was reported to have married morganatically with attempts made to force him to divorce his wife and conduct an equal marriage, but he was reported to have refused. Recent research has disproven claims that the operatic soprano Mafalda Salvatini, an Italian by birth but raised mainly in Paris, and a star at the Berlin State Opera and the Deutsche Oper Berlin, had been his mistress from 1908 until his suicide in 1918 and that her two sons, Charles E. (Horst) Gérard and the set and costume designer and painter Rolf Gérard, were illegitimate children of the Grand Duke.

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