The elusive lightweight, in truth, made Redkach look silly at times when racking up the points to see out a wide decision 99-89 and 98-90 twice with the ringside judges.
A title shot of some kind could now be in the offing for Farmer who has racked up 15 wins since losing for the fourth time in his career against Jose Pedraza in 2012.
Three defeats and a draw in Farmer’s first eight bouts had threatened a stint as a journeyman, although the American has completely turned his form around and looked a different class to his opponent.
Earlier, Amanda Serrano kept a firm grip on her Women’s featherweight title by halting challenger Calixta Silgado.
In an apparent mismatch, Serrano took Silgado out in the first round, breaking the Colombian’s ribs in the process. The champion now boasts a 29-1-1 record.
Also on the bill, Scotland’s Josh Taylor made easy work of Evincii Dixon to make it six wins as a professional.
The 25 year-old ‘Tartan Tornado blasted Dixon out in the second round of what was Taylor’s second fight on American soil.
Ireland’s Conrad Cummings defeated Dante Moore via unanimous decision over six and Jose Gomez enjoyed a victory on the card, whilst Min Wook Kim took just two minutes and thirty-three seconds to dispatch Louis Cruz.