Pita was invited to the ceremony to share stories from his time as a student at the university's Faculty of Commerce and Accountancy, as well as his career in politics.
Before speaking, Pita posted a selfie taken with students in the auditorium at Thammasat’s Rangsit Campus in Pathum Thani. "I have returned to Thammasat University to welcome new friends," read the Facebook caption.
Speaking on the topic "Democracy, Freedom and Justice", Pita said only 20% of the world had democracy compared to 50% when he was a student at university.
He point out that inequality in resource access had worsened, saying only 1% of millionaires in the world owned 50% of global assets, while 50% of people owned only 2% of global assets.
He said democracy, capitalism and freedom as he knew it were being destroyed, as the world was transitioning to the new normal era. He made a strong case for democracy, saying it was a system that enabled people to coexist despite differences in views.
He also blamed the majority of senators for not voting for him to become Thailand's 30th PM, saying that their actions were "injustice".
Senators can vote against and check the PM candidate’s qualifications, but nobody can check a senator’s qualifications, he said.
Speaking of the May 14 election, he said that the new dictatorship group had held elections, but used laws and non-governmental organisations to stop democracy.
Pita said democratic authority should belong to all Thai people to prevent inequality and injustice. He asked students to think bigger and deeper based on national interests.
For instance, students studying engineering should find ways to make tap water drinkable, he said, students studying healthcare should study how to tackle inequality in public health.
He wished students success in their lives, while asking them to believe that they can be what they wanted and be able to change the world.
Pita was recently discharged from hospital after treatment for type A influenza. Doctors asked him to avoid talking as he has not fully recovered yet.
The Move Forward leader failed in his bid to become prime minister last month, while his party appears to be heading for the opposition benches despite winning the May 14 election.
Move Forward’s coalition partner, Pheu Thai, parted ways with the election-winner and its eight-party coalition on Wednesday and is now seeking other partners to form a government.