Halbert was a centreman and first played for Sturt in 1955. In his debut season he finished second in the Magarey Medal count to Lindsay Head and in 1958 was again the runner up with Head winning another Medal. He also polled well in 1960 but again finished second, this time losing to Barrie Barbary. The Medal was finally his in 1961, his 20 votes enough to hold off the challengers. Sturt had actually finished with the wooden spoon that season but it was a good year for Halbert, as well as winning that elusive Magarey Medal he was also picked in the All Australian team after his performances for the South Australians at the Brisbane Carnival. He represented South Australia at interstate football at total of 17 times during his career. In 1962 he was made captain of Sturt and led them to a premiership in 1966, their first flag since 1940. Injuries prevented Halbert from playing in Sturt's 1967 and 1968 premiership sides, and he was forced to retire. He finished with a then club record 251 SANFL games.
In 1979 he became coach of Glenelg, leading them to the 1981 and 1982 SANFL Grand Finals where they were beaten by Port Adelaide and Norwood respectively. He left The Bay after the '82 Grand Final and replaced the legendary coach of Sturt, Jack Oatey in 1983. Halbert would lead the Double Blues to his third Grand Final appearance in three years but again luck was against him when Sturt were defeated by West Adelaide. After the Double Blues could win only eight matches in 1984 and finished seventh, Halbert was replaced as coach by Mervyn Keane. It was his last senior coaching position in the SANFL, although he became a state selector during the late 80s and through the 90s.