Hanns Hubertus was born in Coesfeld in 1901, the son of Imperial Count Reinhard von Merveldt, Baron von Lembeck, and Alice, née Baroness von Beck. In 1920 he began an apprenticeship as a house painter in Münster. He then enrolled at the Baden State Art School and became a master student of August Babberger. In 1924, Merveldt settled in Berlin as a freelance artist. He was able to exhibit in the Salon Gurlitt. Merveldt settled in Paris in 1928, where he got to know Heidi Lenssen. She became his student and his life partner. He was also in close contact with Eugen Spiro and Rudolf Levy at this time. He participated in exhibitions at the Academy of Arts and at the Berlin Art Association, and joined the Berlin Secession. In 1932, Merveldt was awarded the Rome Prize that enabled him to spend a year in the Villa Massimo, from 1933 to 1934. During this time, he became embroiled in a violent dispute with Felix Nussbaum, after which they both had to leave the Villa.
Some sources describe Merveldt as a passionate National Socialist, despite his partner Heidi Lenssen being Jewish. In 1936, Merveldt was represented in the German Pavilion at the Venice Biennale. His partner Lenssen was put under political pressure, so she emigrated to New York in 1936. At the Great German Art Exhibition held at the Munich’s House of German Art (Haus der Kunst) in 1937, assorted paintings were removed after a preliminary inspection by Adolf Hitler, including one by Merveldt. After this, his paintings were removed from other German museums, and he was banned from exhibiting altogether. He then withdrew to Hiddensee. After the war in 1945, the Schanze artists’ community, which had first been active in 1919, was reconstituted in Münster. Merveldt joined them. In 1947 he was made an honorary member of the Munich Secession, and in 1948 he moved to Hamburg.