The ceremony was attended by over 80 foreign officials, including heads of state, ministers and special representatives.
More than 600 Iranian and foreign reporters covered the event.
The president took his public oath of office in front of the Iranian lawmakers and foreign guests, and delivered his inaugural speech.
On Sunday, Pezeshkian received his validation edict from Leader of the Islamic Revolution Ayatollah Seyed Ali Khamenei and officially became the ninth president of Iran.
The parliamentary law stipulates that the new president should present his plans and introduce his ministers within two weeks after inauguration.
The lawmakers will then discuss the credentials of the proposed ministers for a week before holding a final session on the votes of confidence.
Pezeshkian was elected to the Parliament as a representative of the northwestern city of Tabriz in the parliamentary elections on March 1.
After the death of President Ebrahim Raisi in a helicopter crash on May 19, Pezeshkian became one of six final candidates singled out by the Constitutional Council from 80 applicants seeking the presidency.
He won the highest number of votes in the first round of the presidential election on June 28 and faced off the runner-up, Saeed Jalili, in the runoff election on July 5.
The physician-turned-politician won the runoff by garnering 53.66% of the votes.
His new administration, the 14th after the victory of the Islamic Revolution in 1979, holds office for four years.