Leaving school, he worked as a shoe salesman for a year in Limuru, Kenya, using his free time to paint but never showing his work. In 1998 he moved back to Thika, Kenya where he started a small business selling shoes. There he met a few artists who introduced him to the art galleries of Nairobi. Initially painting landscapes and the wildlife of his homeland in oils, he later visited the National Museum's Gallery of Contemporary Art where he found himself inspired to gradually evolve his own unique contemporary style.
He first exhibited in a group exhibition at the Nairobi National Museum 'Art Festival' in 1999, where the reception was so overwhelming that he gave up selling shoes to concentrate on his art.
Current works explore inter-personal relationships and the effects of the political elite on the lives of ordinary folk. He has diversified into sculpture and his monumental metal works now grace esteemed venues such as the forecourt of the Hub Shopping Mall in the high-end suburb of Karen in Nairobi, Kenya. Of his most recent series, Ngugi says “the work is a portrait of real people: their individuality and character is shown through the poses they strike, their choice of clothes and their interaction with other individuals in the frame. Their faces are blank: with no facial features the viewer imagines what their faces look like. My work is a general celebration of the bold colours of Africa; the Continent's strong cultural and social ties and it's diversity.”.
Ngugi has held solo exhibitions in Johannesburg, South Africa and at University of Kentucky, USA., where he also enjoyed a semester-long residency as a beneficiary of the Ruth Hunt Wood Foundation.
His works are held in the collections of State House, Nairobi - the official residence of the President of Kenya; Crown Plaza Hotel, NCBA Bank, Gertrudes Garden Hospital and the East Africa Visual Arts Trust., all in Nairobi, Kenya.