The 142nd Rifle Division was formed as an infantry division of the Red Army in August 1939 in the Leningrad Military District, based on the shtat (table of organization and equipment) of the following month. It participated in the Winter War against Finland as part of 7th Army on the Karelian Isthmus, taking heavy casualties in the fighting for Taipale on the east end of the Mannerheim Line, but gained enough distinction to be awarded the Order of the Red Banner. It remained on the Karelian Isthmus and had a relatively uneventful war facing the Finns until the Vyborg–Petrozavodsk Offensive began on June 10, 1944, from which point it saw much more active service. Attacking northward from much the same place it had begun in the Winter War, now as part of Leningrad Front's 23rd Army, it soon reached the Vuoksi River where it helped stage a successful crossing operation on July 9, and eight of its soldiers became Heroes of the Soviet Union. Shortly after it went on the defense and in September entered the Reserve of the Supreme High Command in preparation for moving to Poland for the final offensive on Germany. The 142nd became part of 2nd Shock Army in 2nd Belorussian Front; its soldiers distinguished themselves in the capture of the German city of Graudenz and later Gdańsk after fighting through northern Poland and Pomerania. As part of the Northern Group of Forces it was disbanded in July 1945.

The division began forming on August 19, 1939, at Malaya Vishera, north of Leningrad, the area where it would spend most of the war. It was based on a rifle regiment of the 49th Rifle Division. Col. Pyotr Stepanovich Pshennikov took command on the day the division formed, and he would be promoted to the rank of Kombrig on November 4. This officer had commanded at brigade and regimental level during the Russian Civil War, and since then had led the 29th Rifle Division before going into reserve; called up again, he had most recently been head of the Leningrad Advanced Training Course for reserve officers. Col. Semyon Petrovich Mikulskii served as his chief of staff.

On November 30 the Winter War with Finland began. The 142nd was part of the Right Wing Operational Group under Komkor V. D. Grendal operated on the eastern flank of 7th Army, near Lake Ladoga. The Group also contained the 49th and 150th Rifle Divisions. On the second day the division occupied Rautu. By December 4 the lead elements of the Operational Group had reached the Mannerheim Line, which was closer to the border on this sector than others. The Finnish commander-in-chief, Marshal C. G. E. Mannerheim, had expected the Soviet forces to first attempt to break the line at Summa, in an effort to reach Viipuri, but in the event Grendal's troops went over to the attack against the Finnish 10th Infantry Division late on December 6 after the artillery had come up.

The 10th Infantry occupied positions north of the frozen Suvanto Waterway and Taipale River, which also contained several coastal artillery batteries. At the confluence of the waterways was a peninsula some 3km wide and 5km long called Koukunniemi. This had been abandoned by the Finns as it was low, marshy, and devoid of cover; they had instead dug in on slightly elevated ground at its base. The Soviet attack started with a heavy artillery preparation lasting four hours. In the advance by the 49th and 150th Divisions that followed an attempt to seize the ferry crossing site at Lossi failed. Many more crossed onto the killing ground of Koukunniemi where they were hit by Finnish artillery fire, losing several hundred casualties. The stunned survivors fled to the south bank in the face of a threatened counterattack.

Over the next several days artillery duels were fought as Grendal's forces probed the Finnish lines for weak points and brought up more guns. A new effort began on December 14 after the two divisions had completely deployed. Soviet artillery strength had increased to 57 batteries, opposed to nine batteries of Finnish field artillery. After an unprecedented bombardment, and using pre-dawn darkness for cover, 30 Soviet tanks began crossing the ice toward the south end of the peninsula, while another 20 rolled toward the northern end at Patoniemi. These were followed by infantry in divisional strength. Fire from the tanks began to cause Finnish casualties. Finally, the Finnish artillery, which had remained silent to this point, opened fire in a planned, methodical fashion. Five minutes of such fire brought the attack to a halt, and 18 tanks were burning. The 142nd now entered the fight, adding even more artillery, but the riflemen performed poorly, milling about under shelling. However the attack persisted, and now Finnish machine gun and rifle fire, along with mortars and grenades, began to take a toll. Minefields and barbed wire under the snow also effectively blocked the advance. In one attack that lasted under an hour 1,000 men were killed and 27 tanks knocked out, largely by the 6-inch coastal guns.

Around December 22 the 4th Rifle Division joined the Group, which now contained 111 batteries of artillery. On December 25, under cover of heavy fog, several groups crossed the Suvanto and took bridgeheads at Patoniemi and Pähkemikkö. After the fog lifted the 10th Infantry counterattacked fiercely, killing some 500 at Patoniemi alone. The crossing at Pähkemikkö was foiled when the visibility revealed the lodgement was in clear view of several machine gun emplacements as little as 100m away. Farther northwest a rifle battalion crossed at Kelja, dug in, and signaled for reinforcements. If these had been available before the fog lifted the entire peninsula could have been cut off, but the reinforcements came under artillery fire while on the ice. 10th Division pressed every available man into battle and Kelja was finally retaken the next morning at considerable cost to both sides.

This marked the end of major Soviet attacks at Taipale until February 1940, but the sector was never actually "quiet". Probes in up to regimental strength continued through January. At the same time the Soviet effort was reorganized, with Leningrad Military District renamed Northwestern Front. Grendal's Group was renamed 13th Army. 7th Army began its renewed offensive at Summa on February 1. During February 10-11 the fighting resumed at Taipale. In a new approach long columns were sent across the ice of Lake Ladoga, but these were at the mercy of the coastal guns. On February 14, in just four hours some 2,500 Red Army men were killed or wounded on the ice. This was followed on February 18 by what was known by the Finns as the "Black Day at Taipale", when the entire 142nd, supported by a huge artillery and air bombardment, struck an untried replacement regiment and drove it off in panic. While the Finnish line was dented, the support line, manned by veterans, held. Despite this minor success, when the war ended on March 13 the 10th Infantry was still holding Taipale, although it was given up under the peace terms. On April 11 the 142nd was awarded the Order of the Red Banner; the 334th Artillery Regiment had been awarded the same four days earlier. Kombrig Pshennikov left the division on April 27 and was replaced by his chief of staff, Mikulskii, who would be promoted to the rank of major general on September 11, 1941. Pshennikov took command of the 36th Rifle Corps and was leading 23rd Army at the start of the Continuation War. He was in command of 3rd Army with the rank of lieutenant general on December 28, 1941, when he was killed in action.

On June 22, 1941, the division was in 19th Rifle Corps of 23rd Army near the Finnish border in Leningrad Military District. The Corps also contained the 115th Rifle Division. Leningrad District was redesignated Northern Front the same day. The 142nd's order of battle was unusual as it contained four rifle regiments instead of the standard three: