After completing his education at Williamstown High School, Sigley's career began in 1952 as a turntable operator on Danny Webb's breakfast program at radio station 3DB Melbourne. Television started in Australia in 1956, and Sigley made his TV debut as host of Teenage Mailbag on HSV-7 in 1957. Shortly after this, he decided to try his luck in London, gaining some work experience at the BBC. But a bigger break was to come with a three-year stint at Radio Luxembourg, where he performed under the name 'Ernie Williams'.
Sigley is remembered by some for his 1964 association with the Adelaide leg of The Beatles tour of Australia. In one press conference, Sigley's questioning of The Beatles about their rock influences, and being able to discuss them (e.g. Buddy Holly), brought about an enthusiastic response from John Lennon, which contrasted strongly from all the questions asked by other interviewers during the conference.
Sigley was host of the afternoon program on Melbourne's 3AW from 1996 until his retirement on Friday 7 November 2008. Regular fill-in presenter Denis Walter replaced Sigley from Monday 10 November 2008.
Sigley then took on a part-time role at the station replacing Paul Cronin as the fill in host on Nightline. Sigley partnered either Bruce Mansfield or Philip Brady in the Friday night slot. Sigley ended his radio career in January 2009 after a 57-year association with the industry, when it is believed he stormed out of a heated meeting with 3AW management.
In the 1960s and early 1970s, Sigley hosted the prime time Adelaide variety show, Adelaide Tonight on NWS-9 and he was the original host of the Australian version of the popular game show, Wheel of Fortune, from 1981 to 1984. In 1982, he presented the regional variety program Six Tonight from BTV-6 Ballarat, and the daytime talent show Pot Luck in 1987.
After a break from television, Sigley returned in 1989 with Denise Drysdale, hosting GTV-9's morning program In Melbourne Today.
From 1974–1976, Sigley was the host of the national Nine Network variety show, The Ernie Sigley Show, featuring notable Australian media personalities such as Denise Drysdale, Noni Hazlehurst, Pete Smith and Joy Westmore. The program was abruptly axed after an off-air outburst by Sigley, directed at station owner Kerry Packer and producer Peter Faiman, when the network cut short his first show for 1976, to accommodate a network sports awards telecast. Packer heard about the incident and flew to Melbourne from Sydney the next day with Don Lane. He dismissed Sigley in person, effective immediately, and replaced him with Lane.
After his dismissal in 1976, Sigley moved to ATV-0 and hosted the early evening variety show Ernie and then in 1979, Saturday Night Live on HSV-7 co-hosting with Mary Hardy.
Sigley was involved in an infamous stoush with fellow TV star Don Lane at a Logies Ceremony in the 1990s. Lane claims that Sigley allegedly made insulting remarks about Lane's partner, Lane then allegedly punched at Sigley.
Sigley began singing in the 1950s, and was a regular on the local Town Hall circuit. In 1957, his first record, Love Is A Golden Ring, was released by W & G Records.
In 1974, Sigley, with Denise Drysdale, recorded the popular duet, Hey Paula, released by Festival Records, Australia and produced at Armstrong Studios, Melbourne. This song went on to be a No. 1 best-selling hit for them in Australia.
Sigley regularly performed around Australia on the club circuit, often with his television partner, Denise Drysdale. More recently he has teamed up with fellow broadcaster and singer, Denis Walter.
Sigley won the TV Week Gold Logie Award for Most Popular Personality on Australian Television in 1975. The award was presented to him by one of his idols, John Wayne.
Sigley, along with his wife, Glenys, supports CBM, a charity working with people experiencing a disability and poverty.
As a boy, Sigley was a choir boy at St Paul's Cathedral, Melbourne.
Three times married and twice divorced, Sigley is married to Glenys (formerly Glenys O'Brien), a multi-Logie award-winning former television personality. They live in the eastern suburbs of Melbourne and have four adult children.
Sigley is also a passionate supporter of the Western Bulldogs (formerly known as the Footscray Football Club). His family announced in October 2016 that Ernie is living with Alzheimer's disease