The first-ever multiparty legislature is part of a peace deal signed in January by the Khartoum government and the former southern rebel Sudan People's Liberation Movement (SPLM).
The former rebels dominate the 170-strong Parliament with 127 members, while the rest of the seats are occupied by the ruling National Congress Party and other southern political groupings.
SPLM secretary general James Wani Igga was elected as parliamentary speaker.
The development now puts south Sudan on the long-awaited path as an autonomous authority for six years, after which the south is due to hold a referendum on secession from the Khartoum government.
Meanwhile, violence persisted in Darfur despite continuing peace talks between Arab militias and Darfuri rebels in the Nigerian capital Abuja.
About 300-armed Arab militiamen attacked Aro Sharow refugee camp in Sudan's north-west Darfur region.
Twenty-nine refugees were killed and 10 seriously injured in the Wednesday-night attack, according to a United Nations High Commission for Refugees (UNHCR) statement.
About 2,5-million Sudanese have fled their homes for makeshift camps to escape violence since fighting broke out in the Darfur region two years ago.
The UN has threatened to stop operations in Darfur after the resurgence of violence in the vast region. -- Sapa-DPA