The inauguration of the National Assembly was the culmination of a UN-backed plan to bring democracy drawn up after U.S.-led forces overthrew the former Taliban regime in 2001.
Former monarch Mohammad Zaher Shah addressed the inaugural session.
"After long years of war and misfortunes, the Afghan people are gathering once again," said Zaher Shah, whose ouster in 1973 by a cousin marked the start of three painful decades of Afghan history. "The inauguration of this national assembly is the determination and demand of the Afghan people. I want from you -- the representatives of the Afghan people -- unity, national solidarity, and the creation of a prosperous Afghanistan. Do your best." (Click here for a timeline of Afghan history.)
Lawmakers were sworn in by President Hamid Karzai, and the oath-taking ceremony was conducted in the country's official Dari and Pashto languages.
"I swear that I will follow the sacred Islamic religion," the oath ran. "I will uphold the constitution and other laws...and I will do my best to fulfill my responsibilities that the people have entrusted me with...and I will fulfill these responsibilities and do it with faith."
After the delegates were sworn in, Karzai called the gathering a display of national unity.
U.S. Vice President Dick Cheney was among guests attending the opening of parliament, which was held amid tight security.
The parliament members were elected in polls held 18 September, the first since 1969.
A new generation of politicians were elected alongside communists, warlords, and former Taliban commanders. One-quarter of the seats in the People's Council (Wolesi Jirga), or lower house of parliament, were reserved for women.
One of parliament's first jobs will be to consider Karzai's cabinet for approval.
(with material from AP/dpa/Reuters)