"I am confident that the members of this parliament ... see there are still some problems threatening our nation. Your mission is very important to restore stability and make the country unite, with stability and peace."
The opening day is largely ceremonial, with the real work getting under way on Tuesday with the election of the speaker of the house.
On Friday, the parties will nominate and vote for Thailand's 25th prime minister, widely expected to be Samak Sundaravej, leader of the PPP.
Thaksin revival
The revival of Thaksin's political fortunes is a serious setback to the army generals, who had deposed him in September 2006.
Thaksin and 110 of his senior officials were banned from politics after the bloodless coup. His once-dominant Thai Rak Thai [Thais Love Thais] party was also disbanded.
However, he remains popular among the rural majority who benefited from his populist policies and voted heavily in favour of his allies in the election.
Sundaravej served as Thaksin's deputy in the mid-nineties and is accused of being a proxy for the former prime minister who is currently out of the country.