Mbuthia's artistic skills are entirely self-taught. He is intensely creative in a variety of media and prolifically so in oil on canvas. He draws inspiration from his own experiences.
Colour is arguably the most important element of Mbuthia's work. Together with his early mentor, Mary Collis, he possesses a natural attribute known as Synesthesia: when he hears a sound, he sees a colour. He uses colour to richly depict emotion; his dreams; political commentary and the general ambience of rural life surrounding his home. His creativity is also evident in the small sculptures, woodcut prints and installation pieces he makes from recycled materials.
Mbuthia is the founder and workshop coordinator of Art Without Borders Kenya. His initiative facilitates a team of artists to bring art to children living in the slums and children's homes and to those confined to the paediatric wards of Kenyatta National Hospital.
He has travelled to both France and the USA to participate in workshops and has been exhibited in Korea, Germany, Tanzania, USA, Paraguay and extensively in Kenya.