- K-0 Pre-production aircraft, powered by a DB 605DM engine
- K-2 proposed version without pressurized cockpit
- K-4 only serial production version without pressurized cockpit, powered by a DB 605DM, DB or DC engine
- K-6 proposed heavy fighter version, as K-4 with reinforced wings holding two additional 30 mm MK 108 cannons and additional armour
- K-8 proposed reconnaissance version, equipment similar to G-8
- K-10 proposed version, similar to K-6, MK 103M engine cannon instead of MK 108
- K-12 proposed version, dual-seat trainer similar to G-12
- K-14 proposed version, similar to K-6, powered by a DB 605L engine
Common Rüstsatz kits, Bf 109K
- R I ETC 501/IX b or Schloß 503belly bomb rack, fusing equipment for fitting a 250 kg (550 lb) or 500 kg (1,100 lb) bomb
- R III Schloß 503A-1 rack for one fuselage drop tank (300 L/80 US gal).
- R IV BSK 16 gun-camera in the left wing between nose ribs 3 and 4.
- R VI two 20 mm Mauser MG 151/20 underwing gunpods with 135 rpg.