Al-Samarraie will follow Mahmoud al-Mashhadani, the former speaker, who resigned last December amid many complaints about his unpredictable behaviour and frequent insults of fellow parliamentarians.
Iraq, which gets 95 per cent of its government revenue from oil exports, had slashed its spending plans and recently delayed passage of the 2009 budget for many weeks.
Although Iraq's political system requires that the speaker be a Sunni Arab, the main Sunni bloc was unable to agree on a candidate until al-Samarraie emerged as a compromise candidate.
Al-Samarraie, who lived in exile in Britain for decades during Saddam Hussein's rule, promised to work towards reform.
"We will do our best to reform parliament and enable it to play a more active role," he said after being elected.