Henrik Gronvold studied art in Denmark and afterwards worked as a draughtsman. At one time he was attached to the Danish Biological Station at Copenhagen as an artist. From 1892 to February 1895 he was employed as an articulator at the British Museum. He then joined a collecting expedition to the Salvage Islands (north of the Canary Islands in the Atlantic Ocean) and upon his return worked unofficially in the British Museum at painting birds, birds' eggs and other specimens. He soon became well-known as an illustrator of books and papers.
Gronvold provided most of the illustrations for The birds of South Africa, by A.C. Stark* and W.L. Sclater*, which was published in four volumes during 1900-1906. In the latter year he became a member of the South African Ornithologists' Union and started contributing to its Journal. As co-author with John A.S. Bucknill* he participated in writing "Remarks upon some hitherto undescribed or unfigured eggs of certain South African passerine birds" (1906, Vol. 2(1), pp. 1-10). They followed this up with a second paper, "Remarks upon some further...eggs of certain South African birds" (1910, Vol. 6(2), pp. 27-33). Gronvold also translated a methodological paper by Prof. A. Reichenow* for the Journal, as "The nomenclature and mode of measuring the external portions of a birds' anatomy" (1906, Vol. 2(2), pp. 115-121).
He illustrated many other bird books, including The birds of Africa (1896-1912) by G.E. Shelley*, The birds of South America (1912-1917) by W.W.K. Brabourne, and The British warblers (1907-1914) by H.E. Howard. In addition he published Illustrations of the game birds and water fowl of South America (1917), containing 38 plates.