Recruited from Healesville in 1966, Halley began in the Essendon under-19s. In 1968 he won the under-19s best and fairest award and was also a member of Essendon's reserves premiership team that year. A ruckman, he started his VFL career two years later, with nine appearances in the second half of the 1970 season. He was called up for national service in 1971 and only played five league games. In 1972 he won Essendon's "best clubman" award in a season in which he played 17 games, including an elimination final. He was mostly in the reserves in 1973 and won the team's best and fairest award.