The 21-year-old scored a try and knocked over three penalties and two conversions against University A to take his season tally past 200 points.
It is only the 22nd time the feat has been achieved since 1976 and Casey, who has scored 13 tries this season, is the first Taieri player to make the list.
But his achievement was rather overshadowed by a surprise loss in the Paul Sapsford Memorial.
The students needed three tries in the last 20 minutes and a penalty on fulltime to defeat the Eels 29-28 in a wonderful match at the University Oval.
Casey went into the match on 194 points and his 18-point haul has taken him to 212 points.
With three rounds remaining, a semifinal and a potential final to play in, Casey's final tally could threaten the record of 260 points set by Dunedin's Daniel Soper in 1997.
Last week, before Casey had brought up the milestone, he told the Otago Daily Times he was not focused on his personal tally.
''I don't keep track of my points at all. As long as I do my job, I'm not too worried,'' he said.
He is pleased with his form, though. When games open up, Casey is at his most dangerous.
He has good pace, a deadly side step and an eye for the gap.
Those attributes have not escaped the attention of Otago coach Cory Brown.
Casey, who has only been playing first five-eighth for two seasons, has been training with the Otago squad for the past three weeks.
He is absorbing as much as he can.
''I'll keep working hard and hope for a crack at the Otago team. Maybe not this season but the one after,'' he said.
Despite Taieri's loss, the team is safely through to the semifinals with 57 points from 15 games.
It has a difficult home fixture against Southern this weekend and will complete the round-robin phase with games against Alhambra-Union on July 4 and Dunedin on July 11.
200 points in season
(since 1976)
260 - Daniel Soper (Dunedin, 1997)
249 - Tutere Williams (Zingari- Richmond, 1997)
235 - Stephen Fenemor (University A, 2012)
231 - Chris Finch (Pirates, 1996)
227 - Brendan Laney (Kaikorai, 1997)
226 - Daniel Soper (Dunedin, 1998)
225 - Chris Finch (Pirates, 1997); Ben Patston (Southern, 2013)
223 - Mike Kenworthy (Kaikorai, 1991); Ryan Bambry (Dunedin, 2003)
215 - Brendan Laney (Kaikorai, 1996); Regan Finch (Pirates, 2006)
212 - Tutere Williams (Zingari- Richmond, 1997); Josh Casey (Taieri, 2015)
211 - Darryl Patterson (Southern, 1990); Dave Ross (University A, 1994)
210 - Tutere Williams (Zingari- Richmond, 1992)
207 - Darryl Patterson (Southern, 1989) 203 - Andre Bell (Southern, 1992); Graeme Dempster (Pirates, 1993)
202 - Glen Porter (Eastern, 1992)
200 - David Halligan (University A, 1981)
