After returning to Sri Lanka upon graduating from Yale in 1972, Senanayake continues to paint, working with motifs of traditional Buddhist art and the Sri Lankan flora and fauna. His paintings are classic manifestations of the fundamental belief that art should spring from the need to express feelings and emotions. His work “Untitled (Tea Pickers)” from 1977, which was recently auctioned at the reputed art gallery and auction house Sotheby’s London, displays his preference for brilliantly coloured scenes of rich, overlapping jungle fauna and vegetation. The Sri Lankan landscape combined with the traditions of Buddhist is evident in this painting that depicts figures of female tea pluckers surrounded by the lush green hues of a tea plantation. In 1983, he won an award as one of the ten outstanding young people of the world by the Jaycee International for his contribution to the art industry in Sri Lanka and the world. 

In the last decade or so, Senanayake has been working on the theme of the preservation of rainforests, having been exposed to the plight of Sri Lankan rainforests as sites of which 70% has been destroyed due to cash crops and food cultivation. Of his decision to choose this theme to dominate the next stage of his artistic career, he said, “I decided to use my skills as a painter to enlighten the public about our crisis. By highlighting the beauty of rainforests, I was able to bring about awareness. As we all have only one world to live in, I decided to create images from rainforests of the world and make my project international.” Since the early 2000s he has been working towards spreading awareness about the need to preserve rainforests with exhibitions held internationally in the USA, UK and India. In 2018, he held a solo exhibition of his paintings at the Grosvenor Gallery in London, UK focusing on endangered flora and fauna. The painting “Butterflies” is an aesthetically appealing piece, depicting four butterflies entangled in the scent of lotus flowers on water. The colours, as expected, are rich, and an ecology in which flora and fauna depend on each other for survival is captured with distinct shapes embedded in the flowers and the butterflies that overlap. Traces of impressionism and colourism can be seen in this painting, with its thin but visible brush strokes that highlight the natural lighting of the rainforests and the passage of time with ordinary subject matter. 

Senanayake is one of the few artists who draws for everyone in the community, and not just a chosen crowd that practice a more intellectual approach to art. Once he declared, “I consider myself a people’s artist. Many artworks are totally ignored by the average person. I would be disappointed if it happened to me.” His paintings are on permanent display at the Parliament of Sri Lanka, the President’s House, the Central Bank of Sri Lanka as well as several major hotels such as the Galle Face Hotel and the TajSamudra, while his sculptures have been placed at the Grindlays Bank and the Hatton National Bank Head Office in Colombo. He lives and works from his house in Colombo, which reflects the style of his vibrant paintings, with a tropical garden full of flowers in bloom on lush greenery. He hopes to continue spreading awareness about protecting rainforests with “positive paintings” to which everyone can relate.