Derrinallum achieved significant success across its 75 years in the Western Plains league. They won their first WPFA premiership in 1922, a year after finishing runner-up. While success would elude them until 1960 – a premiership which was bookended by eight grand final losses, four either side of that fateful victory over Cressy – it was clear that by their third premiership in 1971, Derrinallum was a powerhouse of the competition. The club would win a further five flags over the next decade, capped off by their 87-point trouncing of Lismore in 1981.
Ultimately, in 27 WPFL seasons from 1959 until 1985, Derrinallum played in 17 grand finals for 8 premierships. A further runner-up finish occurred in 1992, before Derrinallum finally broke – what was, by their lofty standards – a lengthy 15-year premiership drought in 1996 with their six-point defeat of Skipton in the grand final. One final runner-up finish was bestowed on Derrinallum in 1997, before the club fell to its knees. Derrinallum did not take part in either the seniors or reserves in the 1998 WPFL season, and while this may have contributed to the strength of their thirds side – who would win that year's grand final by a whopping 121 points over Carngham-Linton – the overall health of the club was poor.
Nearby Mortlake, also struggling with a lack of players, approached Derrinallum with a merger proposal, and the Western Lions Football Netball Club was formed in 1999 as an amalgamation of Derrinallum and Mortlake. While the majority of Derrinallum supporters were in favour of the merger, a breakaway group pursued a future with Lismore instead, owing to its closer location along the highway. Those who doubted the Western Lions venture cited the belief that Derrinallum would form the weaker half of the merger given Mortlake was a major league (Hampden) club, and that eventually Derrinallum's identity would cease to exist.
Many would argue that prescience proved true. Lismore agreed to its own merger with Derrinallum ahead of the 1999 season, while the Western Lions played concurrently – both sides featuring ex-Derrinallum players. The struggling Lions entered recess in April 2000 and eventually formed a merger with Terang more than a year later to become Terang-Mortlake for the 2002 season. Derrinallum's history and assets remained at the Mortlake ground as part of Terang-Mortlake as of mid-2003, while its name and physical presence still lives on as part of the Lismore-Derrinallum Football Netball Club to this day, due to the fact Lismore-Derrinallum plays half of its home games at the Derrinallum Recreation Reserve.