Pezeshkian, on his first Kremlin visit since winning the presidency last July, will hold talks with Putin focusing on bilateral ties and international issues before signing the treaty.
Ahead of the talks, the Kremlin hailed its ever closer ties with Tehran.
“Iran is an important partner for us with which we are developing multifaceted co-operation,” Kremlin spokesperson Dmitry Peskov told reporters.
Moscow has cultivated closer ties with Iran and other countries hostile towards the U.S., such as North Korea, since the start of the Ukraine war, and already has strategic pacts with Pyongyang and close ally Belarus, as well as a strategic partnership agreement with China.
The 20-year Russia-Iran agreement is not expected to include a mutual defense clause of the kind sealed with Minsk and Pyongyang, but is still likely to concern the West which sees both countries as malign influences on the world stage.
Moscow and Tehran say their increasingly close ties are not directed against other countries.