Before entering politics, he worked in construction organizations in the Chelyabinsk, Orenburg and Moscow regions.

From 1959 to 1969 he worked as a fitter at the Kopeysk Coal trust, as a bricklayer at the Chelyabinsk Civil Construction trust, then as a foreman, technologist, shop manager, head of department, chief engineer of the Orenburg precast concrete plant.

On 16 October 1991, by decree of the President of Russia Boris Yeltsin, Tyazhlov was appointed Head of Administration of Moscow Oblast.

On 19 December 1999, at the second gubernatorial elections, he came fourth (13% of the vote) and dropped out of the race.

Tyazhlov also ran for the 3rd State Duma from the Fatherland – All Russia bloc and became one of the deputies of the lower house (1999–2003).