Earlier this month, the struggling Tykes travelled to the Hatters for a second tier clash, which was level at 1-1 early in the second half.
Fred Onyedinma then went through on goal, brought down by keeper Bradley Collins, for what was an obvious penalty.
The visiting players surrounded referee Andy Davies though, striker Carlton Morris claiming a handball in the build-up, with Collins almost refusing to allow the kick to be taken, standing on his six-yard line while Elijah Adebayo waited patiently, something Town chief Nathan Jones labelled as 'disrespectful' afterwards.
The forward hammered home the resulting penalty into the top corner, with Collins then booked for his complaints, as Town eventually went on to triumph 2-1.
Barnsley had denied the claims, but a statement from the FA said: "Barnsley FC has been fined £10,000 for a breach of FA Rule E20.1 that occurred at its game against Luton Town FC on Tuesday 8 February 2022 in the EFL Championship.
"The club denied failing to ensure that its players conducted themselves in an orderly fashion during the 57th minute.
"However, an independent Regulatory Commission found the allegation to be proven and imposed this sanction during a subsequent hearing."
Earlier this month the club were fined £12,000 for a similar breach during their home defeat by Cardiff.