Crews from North Yorkshire and Humberside fire services were called to the property at Barlby Road, Selby just after 7pm last night (Friday).
There was no-one at home when the fire broke out but smoke detectors went off.
There was fire, heat and smoke damage to living room and smoke damage to the remainder of the flat.
A spokesperson for North Yorkshire fire said the cause was "believed to be a candle left unattended".
Four fire fighters wearing breathing apparatus went into the flat and used two hose-reel jets, a thermal imaging camera, lights and a pressure ventilation fan to tackle the blaze.