In the two semi finals,
St. George beat second-placed
Eastern Suburbs whilst minor premiers
Western Suburbs beat defending premiers
South Sydney. The two winners then played a final in which St. George upset Western Suburbs 14–6, as they previously did in Round 11. The finals system set in place then forced the final to be replayed, in what was known as the "Right of Challenge". This system ensured that in the event that the minor premiers lost in either the first or second round of the finals, then regardless they would be given a second chance in a premiership decider. With this being the first season where the "Right of Challenge" was exercised, the 1930 decider was thus the first "grand final" played in the NSWRFL. {{Round4
Final Having pipped Eastern Suburbs 11–10 at their home ground of Earl Park on 20 September, Saints continued their good form into the following weekend in the final, defeating
minor premiers Western Suburbs 14–6 in front of 16,557 people. The two teams had met twice before during the season with Wests winning the first encounter in May and St. George winning the second match in August. Under the previous system, victory in the final would have seen St. George declared premiership champions. However, in 1930, Wests were allowed a second chance as minor premiers if defeated during the finals.
Grand final The re-match decider was played in front of 12,178 people on 4 October at the
Sydney Sports Ground and officiated by referee Lal Deane.
St. George led 2–0 early and competed in the first half. However,
Western Suburbs were a crack outfit and after Saints lost veteran forward, Harry Flower with an arm injury, they skipped away to a 16–2 lead. Wests eventually ran in seven tries and crushed St. George 27–2 to take away their first ever NSWRFL premiership in any grade, although they were one of the foundation clubs in 1908. It was the final game as a player for Wests’ captain-coach and versatile representative star Jim Craig.
Western Suburbs 27 (Tries: Alan Brady 3, Jim Craig, Charlie Cornwell, Ray Morris, Cecil Rhodes. Goals: Jim Craig 2, Bill Brogan)
St. George 2 (Goals: Bill Hyland) Image:Frank McMillan.jpg|
Frank McMillan Image:Jim Craig Australian Rugby League.jpg|
Jim Craig Image:Snowy_Justice.jpg|
Arthur Justice ==Notes==