| 1989–90 | 20 May 1990 | Sydney Olympic | 2-0 | Marconi Stallions | Parramatta Stadium, Sydney | 26,353 |  From 1977–1983 and 1987, the top placed team at the end of the regular season was declared champion. However a compromise format was devised between the traditional first past the post system and the Australian system of finals. A Playoff series was conducted in these years except for the 1977, 1981 & 1983 seasons, however the winner of the Playoff Series didn't become champion of the NSL.
| Season | Grand Final Date | Winning Team | Score | Losing Team | Location | GF Attendance | | 1978 | 17 September 1978 | Sydney City | 4-2 | Marconi Stallions | Sydney Sports Ground, Sydney | 9,136 | | 1979 | 28 October 1979 4 November 1979 | Sydney City | 1-0 1-1 | Brisbane City | Wentworth Park, Sydney Perry Park, Brisbane | 2,532 4,200 | | 1980 | 26 October 1980 | Heidelberg United | 4-0 | Sydney City | Canberra Stadium, Canberra | 11,126 | | 1982 | 3 October 1982 | St George | 3-1 | Sydney City | Penrith Stadium, Sydney | 6,495 | | 1987 | 1 November 1987 | St George | 4-0 | APIA Leichhardt | Parramatta Stadium, Sydney | 6,961 |
''The numbers in brackets indicate the number of playoff series won by a team, or the number of Grand Finals held in a city.'' The NSL also held a cup competition, which was held initially during the regular season, before gradually becoming a pre-season warm-up tournament. It was discontinued after the 1996–97 season.
| Season | Cup Final Date | Winning Team | Score | Losing Team | Location | Cup Final Attendance | | 1977 | 9 October 1977 | Brisbane City | 1-1 | Marconi Stallions | Perry Park, Brisbane | 9,000 | | 1978 | 8 October 1978 | Brisbane City | 2-1 | Adelaide City | Perry Park, Brisbane | 6,964 | | 1979 | 30 September 1979 | Adelaide City | 3-1 | St George | Olympic Sports Field, Adelaide | 9,554 | | 1980 | 5 October 1980 15 October 1980 | Marconi Stallions | 0-0 3-0 | Heidelberg United | Olympic Park, Melbourne Marconi Stadium, Sydney | 7,000 5,000 | | 1981 | 20 September 1981 | Brisbane Lions | 3-1 | West Adelaide | Canberra Stadium, Canberra | 6,132 | | 1982 | 12 September 1982 | APIA Leichhardt | 2-1 | Heidelberg United | Olympic Park, Melbourne | 7,000 | | 1983 | 6 November 1983 13 November 1983 | Sydney Olympic | 1-0 1-0 | Heidelberg United | St. George Stadium, Sydney Olympic Park, Melbourne | 9,420 6,000 | | 1984 | 13 September 1984 | Newcastle Rosebud United | 1-0 | Melbourne Knights | Olympic Park, Melbourne | 5,000 | | 1985 | 11 August 1985 | Sydney Olympic | 2-1 | Preston Lions | St. George Stadium, Sydney | 11,187 | | 1986 | 17 September 1986 | Sydney City | 3-2 | West Adelaide | Hindmarsh Stadium, Adelaide | 5,200 | | 1987 | 14 October 1987 18 October 1987 | Sydney United | 1-0 1-0 | South Melbourne | St. George Stadium, Sydney Olympic Park, Melbourne | 5,845 6,000 | | 1988 | 14 August 1988 | APIA Leichhardt | 0-0 | Brunswick Juventus | Marconi Stadium, Sydney | 5,200 | | 1989 | 20 August 1989 | Adelaide City | 2-0 | Sydney Olympic | Hindmarsh Stadium, Adelaide | 10,000 | | 1989–90 | 25 April 1990 | South Melbourne | 4-1 | Sydney Olympic | Olympic Park, Melbourne | 7,000 | | 1990–91 | 7 April 1991 | Parramatta Eagles | 1-0 | Preston Lions | Marconi Stadium, Sydney | 8,749 | | 1991–92 | 7 April 1992 | Adelaide City | 2-1 | Marconi Stallions | Hindmarsh Stadium, Adelaide | 6,500 | | 1992–93 | 18 April 1993 | Heidelberg United | 2-0 | Parramatta Eagles | Marconi Stadium, Sydney | 4,596 | | 1993–94 | 17 October 1993 | Parramatta Eagles | 2-0 | Sydney United | Marconi Stadium, Sydney | 5,156 | | 1994–95 | 16 October 1994 | Melbourne Knights | 6-0 | Heidelberg United | Olympic Park, Melbourne | 6,000 | | 1995–96 | 27 January 1996 | South Melbourne | 3-1 | Newcastle Breakers | Lakeside Stadium, Melbourne | 5,000 | | 1996–97 | 6 October 1996 | Collingwood Warriors | 1-0 | Marconi Stallions | Lakeside Stadium, Melbourne | 2,327 |
''The numbers in brackets indicate the number of cups won by a team, or the number of Cup Finals held in a city.'' The NSL also had a national youth competition, consisting of a variety teams, both from within and outside of the NSL's membership. The competition began in 1984, and was ended at the same time as the NSL, in 2004.
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