The 1977 Australian Open (December) was a tennis tournament played on outdoor grass courts in Melbourne, Victoria, Australia. It was the 66th edition of the tournament and was held from 19 to 31 December 1977. Due to a scheduling change two Australian Opens took place in 1977 with the first taking place in January. Vitas Gerulaitis and Evonne Goolagong Cawley won the singles titles.

Seniors

Men's singles

🇺🇸 Vitas Gerulaitis defeated 🇬🇧 John Lloyd, 6–3, 7–6, 5–7, 3–6, 6–2

Women's singles

🇦🇺 Evonne Goolagong Cawley defeated 🇦🇺 Helen Gourlay Cawley, 6–3, 6–0

Men's doubles

🇦🇺 Ray Ruffels / 🇦🇺 Allan Stone defeated 🇦🇺 John Alexander / 🇦🇺 Phil Dent, 7–6, 7–6

Women's doubles

🇦🇺 Evonne Goolagong Cawley / 🇦🇺 Helen Gourlay Cawley vs. 🇺🇸 Mona Schallau Guerrant / 🇦🇺 Kerry Melville Reid, shared due to rained out final

Mixed doubles

Juniors

Boys' singles

🇦🇺 Ray Kelly

Girls' singles

🇦🇺 Amanda Tobin defeated 🇦🇺 Leanne Harrison, 6–1, 6–2