The afternoon didn’t go as planned, but it shouldn’t take away from a monumental achievement. He joins a list of only other 14 Owls players to have achieved the feat.
The first of those 400 appearances came as Palmer made his Wednesday debut in midfield, in an August 2010 League Cup match against Bury.
The Owls won 1-0 thanks to a Giles Coke winner - but who else played in the match - and which two future Wednesday players featured for the opposition?
Here’s a run through memory lane.
5. Mark Beevers
Another Wednesday academy alumni, Beevers was a popular figure at S6 and has made over 100 appearances for four EFL clubs - Wednesday, Millwall, Bolton and Peterborough. Was briefly linked with a return to Hillsborough last year. Now plays in Australia with Perth Glory. | Getty Images
6. Jon Otsemobor
A Liverpool youth man of some repute, his career with Wednesday never quite got going - though he did have a scrap with Reda Johnson in the Middlewood Road car park. The full-back left S6 for MK Dons in 2012 and retired aged 32 two years later. Now in property development. | Getty Images
7. Darren Potter
Another Liverpool youth who signed for Wednesday in 2009 and made over 100 appearances. Signed for MK Dons to great success two years later, retiring after spells with Rotherham and Tranmere in 2020. Went into coaching and has held roles at Port Vale and Stoke City. | Getty Images
8. Liam Palmer
Operated on debut in what was then his natural position - in midfield - Palmer spent time on loan with Tranmere where he cut his teeth in 2012/13. Has the unique distinction of having played roles in two League One promotion campaigns with the Owls and celebrated his 400th appearance at Cardiff on Saturday. A club icon, Palmer entered Owls immortality last season with his 98th minute play-off goal against Peterborough. | Getty Images