He was educated at Synge Street Christian Brothers School, and in 1915 was apprenticed to the stained glass studios of Joshua Clarke.
[1][4][3] In 1917, MacGonigal was enlisted into Na Fianna Éireann by Bulmer Hobson, serving as an IRA dispatch rider during the War of Independence reporting to Sean Dowling in C Coy, 4th Battalion, Dublin Brigade.
[1] MacGonigal was made a partner with Harry Clarke, working as a designer while an evening student at Dublin Metropolitan School of Art.
[1] Following a visit to the Netherlands in 1927 to study in The Hague,[2] MacGonigal was influenced by the work of Anton Mauve and Vincent van Gogh.
His work, A Dublin studio, includes fellow members such as Séan Keating, Harry Kernoff, Frank O'Connor, and Seán O'Sullivan.
From 1937 to 1954, MacGonigal served as assistant professor of painting at the newly reformed National College of Art (NCA) under Keating.
MacGonigal resigned as professor in NCA in response to the 1969 student revolt against the conservative curriculum, citing an erosion of the educational authority of the teachers.
He was a critic of the Irish government's tax-free status to creative artists brought into effect in 1969, stating that it would bring "the art parasites of Europe" to Ireland.
In 1971 he sat on the advisory committee of the Project Art Centre, Dublin, and from 1972 was an elected member of the Water Colour Society of Ireland.