Born in Dublin, McGuinness was a landscape painter who began his career as an architect, exhibiting his drawings and designs at the RHA. Subsequently, McGuinness starting taking evening classes at the RHA where he discovered his passion for painting. He traveled to Dusseldorf to pursue his study further. When re returned to Dublin he actively became involved in many artists groups including the Dublin Sketching Group and the Watercolour Society of Ireland. He began exhibiting at the RHA in 1866 , exhibiting more than 150 works in the next sixty years. He also exhibited in the Royal Academy in London.