In 1959, Smither returned to New Plymouth, working part-time in arts-related jobs. His first solo exhibition was in 1961. In 1963 he married Elizabeth Harrington, who is better known as New Zealand Poet Elizabeth Smither. The two have three children, Sarah, Thomas and Joseph.
Smither separated from Elizabeth and eventually divorced. For a few years he was married to Rachel McAlpine, a writer. Smither now lives at Otama beach on the Coromandel Peninsula.
Smither was also influenced by Rita Angus and Lois White as he was studying. He turned to them for inspiration.
Smither works in a variety of media - notably oils, acrylics, and screenprint - and on a variety of subjects. Domestic life is a major theme of many of his works, these scenes depicted with a rigorous yet idiosyncratic realism. A similar style is brought to his landscapes, many of which depict the Taranaki landscape around which he grew up. At least two of his paintings, The Family in the Van and Rocks with Mountain have attained the status of iconic paintings in New Zealand.