His father ran a timber and hardware business in Melbourne before settling the family on a farm in Greenval in 1932.

During World War II he managed the family farm in the absence of his older brothers, and also joined the Air Training Corps.

In 1948, he joined J. J. Webster Pty Ltd, the Elsternwick timber, hardware, and plumbing retailer that had been founded by his grandfather in 1884.

[1] Webster was appointed to the Senate in December 1964, filling a casual vacancy caused by the death of Harrie Wade.

[4] In 1975, his constitutional eligibility to sit in the Senate was questioned, prompting the Parliament to introduce the Common Informers (Parliamentary Disqualifications) Act 1975, although ultimately the High Court found that he was not ineligible and he continued to serve until his retirement in 1980.

[5][6] In December 1979, it was announced that Webster would retire from politics in order to be appointed High Commissioner to New Zealand.

[8] Webster served as High Commissioner during the negotiations leading up to the Closer Economic Relations agreement.

According to John Menadue, he opposed the Fraser government's 1981 changes to the Trans-Tasman Travel Arrangement, which required New Zealanders to carry passports when entering Australia.