The 21-year-old slotted five conversions and two penalties during the Eels' 46-8 win against Dunedin at Peter Johnstone Park on Saturday.
His 16-point bag saw him overhaul Daniel Soper's record season tally of 260 points scored for Dunedin in 1997.
Casey was on 259 points before the game and brought up the milestone with a penalty in the 25th minute.
''It was sort of on my mind a bit at the start of the game, so I was happy to get an early penalty and get it out of the way,'' Casey said.
''I'm pretty happy with the achievement. It is something I never really set out to do. It sort of just happened.''
Last winter, Casey broke another premier club record.
He amassed 47 points during Taieri's 127-12 romp against Green Island to surpass the previous mark of 42 posted by University A's Guy Curtis since 1993.
It is also worth noting Casey has scored 16 tries this season.
Only seven players have score more tries.
Southern's Steve Dunn holds the record.
He scored 26 in 1997.
Hayden Reid (University A) in 1999 and Roy Hawker (University A) in 2000 scored 19.
Four players, including Casey's team-mate Kori Rupene, have scored 17 tries.
With the Eels safely through to the playoffs, Casey will have an opportunity to extend his season tally.
He needs another 25 points to reach 300 points.
While it seems unlikely he will accumulate those points during the semifinal against Southern at Forsyth Barr Stadium this Saturday, Casey has scored 32 points in a game three times this season.
And should Taieri reach the final, there is every chance he could break the 300-point barrier.
The semifinal will pit Casey against another prolific scorer. Southern's Bryce Hosie (216 points) brought up 200 points during his side's 24-22 win against Harbour at Bathgate Park on Saturday.
''In the next couple of games, goal kicking is going to be pretty important, so hopefully I can kick a few more over for the boys. But I'm only focused on winning this weekend against Southern and hopefully we can get through to the final.''
Detailed records have only been kept since 1976.
