Khomitsky, 40, was still trying to find his feet against the unbeaten Etches when unleashing a big shot in the fourth from which the Yorkshireman never recovered.
The loss brings to an end Etches previously perfect 18-0 record, whilst Khomitsky takes home another UK scalp and the IBF International middleweight title into the bargain.
Prior to the big KO and in an entertaining battle, Gavin McDonnell followed his brother Jamie by winning a European title as the Doncaster man out-pointed Oleksandr Yegorov.
McDonnell was easy to hit at times and struggled to find Yegorov’s chin a lot of the time, but was still awarded a handy victory on the judges’ scorecards.
Cards of 118-109, 118-110 and 117-11 were read out in favour of the Briton, although Yegorov could argue to at least have been given a couple more rounds.
Frankie Gavin made easy work of the unheralded Bogdan Mitic without wowing the Sheffield crowd on the former world amateur champion’s ten-round Matchroom Boxing debut.
The 29 year-old is lined up to fight Chris Van Heerden for a fringe version of the IBF welterweight title on May 9, but will have to up his game considerably against the dangerous South African next time around.
‘Funtime’ proved to be a less-than descriptive name for the Birmingham fighter’s performance, although Gavin was never in any trouble and did what he had to do with aplomb to take the contest 100-90.
Earlier, Stephen ‘Swifty’ Smith warmed up for a potential world title fight at super featherweight with a decisive points win over Jacek Wylezol.
Liverpool-based Smith made a successful return from injury by taking every round of six to walk away with a 60-53 triumph.
The 29 year-old has impressed since moving up to 130lbs on the back of a shock stoppage loss to Lee Selby at featherweight in 2011. Smith’s record now reads 21-1 with 12 early finishes.
Kal Yafai was made to work harder than expected to secure an eight-round decision victory over Nicaraguan champion Cristofer Rosales. The talented Yafai, 25, boxed his way to a 79-76 points win and moves on to be part of the Gavin v Van Heerden undercard in a few weeks.
Jordan Gill and Leigh Wood breezed to wins on the card as Gill took every session from Barrington Brown and Wood knocked out journeyman Laszlo Feketas in the first round.