Johnson was credited with 34 individual victories over enemy aircraft, as well as seven shared victories, three shared probable, 10 damaged, three shared damaged and one destroyed on the ground. Johnson flew 700 operational sorties and engaged enemy aircraft on 57 occasions. Included in his list of individual victories were 14 Messerschmitt Bf 109s and 20 Focke-Wulf Fw 190s destroyed making him the most successful RAF ace against the Fw 190. This score made him the highest scoring Western Allied fighter ace against the German Luftwaffe.