Born to a poor peasant family from the Don Cossack region in southern Russia, Budyonny was drafted into the Imperial Russian Army in 1903.

He received the blame for many of Stalin's military strategic errors in the early part of World War II, but he was retained in the Soviet high command.

During the Great Purge, he testified against Mikhail Tukhachevsky's efforts to create an independent tank corps, claiming that it was so inferior to cavalry and illogical that it amounted to "wrecking" (sabotage).

'"[2] Budyonny was born into a poor peasant family on the Kozyurin farmstead near the town of Salsk in the Don Cossack region of the southern Russian Empire (now Rostov Oblast).

He worked as a farm labourer, shop errand boy, blacksmith's apprentice, and driver of a steam-driven threshing machine, until the autumn of 1903, when he was drafted into the Imperial Russian Army.

[3]: 9–12 During World War I, Budyonny was the 5th Squadron's non-commissioned troop officer in the Christian IX of Denmark 18th Seversky Dragoon Regiment, Caucasian Cavalry Division on the Eastern Front.

However, there was general ineptitude among the officers under whom he served (primarily Caucasian aristocrats who received commissions based on their social standing).

He was involved in a heated confrontation with the squadron sergeant major regarding the officers' poor treatment of the soldiers and the continual lack of food.

On the night of 23 February, Budyonny organized a force of 24 men to retake Platovskaya from the white guards, but was soon joined by a large number of new recruits.

Both supported the idea of creating a cavalry corps to fight on the Bolshevik side in the Russian Civil War; but when Leon Trotsky, the People's Commissar for War, visited south Russia soon afterward, he told Budyonny that cavalry was "a very aristocratic family of troops, commanded by princes, barons, and counts."

During the summer of 1919, while the Red Cavalry were in action against the White General Anton Denikin, Trotsky described them contempuously as "Budyonny's corps — a horde, and Budyonny — their Ataman ring leader...He is today's Stenka Razin, and where he leads his gang, there will they go: for the Reds today, tomorrow for the Whites.

"[5] However, in October 1919, Budyonny pulled off a spectacular victory when, in the greatest cavalry battle of the civil war, he attacked and defeated the White army corps commanded by Konstantin Mamontov.

On 25 October, Trotsky sent a dispatch forecasting that the White army in the south would never recover from this defeat, and hailing Budyonny as "a true warrior of the workers and peasants".

On 15 August, he asked the commander-in-chief of Soviet forces in Poland, Mikhail Tukhachevsky, for authority to swing north and assist in capturing Warsaw.

[7] The writer Isaac Babel rode with Budyonny's cavalry in Poland, and published a series of short stories about the experience, which achieved worldwide acclaim as one of the greatest contributions to Soviet literature – but which offended Budyonny, who made a "rare and furious foray into print" in March 1924, demanding that the Red Cavalry's reputation should be protected against "slander" by a "literary degenerate".

Thereupon Budyonny called over a harmonic player and went into a spin, cutting a Cossack caper with the ease and grace of a youngster.

In 1923, Budyonny arrived in Chechnya with a proclamation from the Central Executive Committee announcing the formation of the Chechen Autonomous Region.

He spent a great amount of time and effort in the organization and management of equestrian facilities and developing new breeds of horses.

[10] This brought him into direct conflict with Tukhachevsky, who was in charge of weapons developed, and foresaw the imminence of mechanized warfare.

When Bukharin was trying to defend himself, during a plenum of the Central Committee of the Communist Party of the Soviet Union, on 26 February 1937, Budyonny barracked him, calling him a Jesuit.

[11] On 24 May 1937, Budyonny was copied into a resolution proposing to arrest Marshal Tukhachevsky, and the high ranking party official Janis Rudzutaks.

At the trial, he provided testimony that Tukhachevsky's efforts to create an independent tank corps was so inferior to horse cavalry and so illogical that it amounted to deliberate "wrecking".

By December 1937, Budyonny had been allocated a large dacha with orchards, raspberry and gooseberry bushes, a workhorse, a black cow and a pig weighing 250 kilograms (550 lb).

"[17] German Field Marshal Rundstedt, commander of Army Group South in the battles of Kiev and Uman, said after the war: "Of Budyonny, who commanded the armies facing me, a captured Russian officer aptly remarked — ‘He is a man with a very large moustache, but a very small brain.’"[18] Because of his exceptional Civil War record and public popularity, he continued to enjoy Stalin's patronage and suffered no real punishment for the disaster in Kiev.

Pallbearers at his funeral included the General Secretary of the CPSU Leonid Brezhnev and the USSR Minister for Defence, Marshal Grechko.

Budyonny wrote a five-volume memoir, in which he described the stormy years of civil war as well as the everyday life of the First Cavalry Army.

Mikhail Soloviev, a Soviet army officer who settled in the west after being captured early in the German–Soviet War, alleged that Budyonny killed his wife after she had confronted him over his infidelity.