To take advantage of the new engine, the Council of Ministers ordered the Mikoyan-Gurevich OKB to build two prototypes for an advanced high-altitude daytime interceptor to defend against bombers. It was to have a top speed of 1,000 kilometres per hour (620 mph) and a range of 1,200 kilometres (750 mi).

Designers at MiG's OKB-155 started with the earlier MiG-9 jet fighter. The new fighter used Klimov's British-derived engines, swept wings, and a tailpipe going all the way back to a swept tail. The German Me 262 was the first fighter fitted with an 18.5° wing sweep, but it was introduced merely to adjust the centre of gravity of its heavy Junkers Jumo 004 pioneering axial-compressor turbojet engines. Further experience and research during World War II later established that swept wings would give better performance at transonic speeds. At the end of World War II, the Soviets seized many of the assets of Germany's aircraft industry. The MiG team studied these plans, prototypes and documents, particularly swept-wing research and designs, even going so far as to produce a flying testbed in 1945 to investigate swept-wing design concepts as the piston-engined "pusher"-layout, MiG-8 Utka (Russian for "duck", from its tail-first canard design). The swept wing later proved to have a decisive performance advantage over straight-winged jet fighters when it was introduced into combat in Korea.

The design that emerged had a mid-mounted 35-degree swept wing with a slight anhedral and a tailplane mounted up on the swept tail. Western analysts noted that it strongly resembled Kurt Tank's Focke-Wulf Ta 183, a later design than the Me 262 that never progressed beyond the design stage. While the majority of Focke-Wulf engineers (in particular, Hans Multhopp, who led the Ta 183 development team) were captured by Western armies, the Soviets did capture plans and wind-tunnel models for the Ta 183. The MiG-15 bore a much stronger likeness to the Ta 183 than the American F-86 Sabre, which also incorporated German research. The MiG-15 does bear a resemblance in layout, sharing the high tailplane and nose-mounted intake, although the aircraft are different in structure, details, and proportions. The MiG-15's design understandably shared features and some appearance commonalities with the MiG design bureau's own 1945–46 attempt at a Soviet-built version of the Messerschmitt Me 263 rocket fighter in the appearance of its fuselage. The new MiG retained the previous straight-winged MiG-9's wing and tailplane placement while the F-86 employed a more conventional low-winged design. To prevent confusion during the height of combat the US painted their aircraft with bright stripes to distinguish them.

The resulting prototypes were designated I-310. The I-310 was a swept-wing fighter with a 35-degree sweep in wings and tail, with two wing fences fitted to each wing to improve airflow over the wing. The design used a single Rolls-Royce Nene fed by a split-forward air intake. A duct carried intake air around the cockpit area and back together ahead of the engine. Its first flight was 30 December 1947, some two months after the American F-86 Sabre had first flown. It demonstrated exceptional performance, reaching 1,042 kilometres per hour (647 mph) at 3,000 metres (9,800 ft).