The 66-year-old opposition leader's entry into the legislature heralds a new political era in Myanmar, cementing a risky detente between her party and the reformist government of President Thein Sein, which inherited power from the army last year.
Suu Kyi's National League for Democracy party will occupy too few seats to have any real power in the ruling-party dominated assembly, however, and there are fears the presence of the opposition lawmakers could simply legitimize the regime without any change.
But the new lawmakers are also likely to bring a level of public debate to the legislative body that has never been seen as they prepare for the next general election in 2015. The swearing-in ceremony took place in the capital, Naypyitaw, which was built by the former army junta.
With white roses in her hair, Suu Kyi stood along with several dozen of her party's lawmakers as the speaker of the lower house asked them to read the oath. Suu Kyi's ascent marks an astonishing reversal of fortune for a woman who became one of the world's most prominent prisoners of conscience, held under house arrest for much of the last two decades.
When the 1991 Nobel Peace Prize winner was finally released in late 2010, just after a vote her party boycotted that was deemed neither free nor fair, few could have imagined she would make the leap from democracy advocate to elected official in less than 18 months.