The success of Mr Maliki's non-sectarian State of Law coalition in provincial polls in Baghdad and the Shiite south gives a leader once derided as weak a mandate for a strong central state, and crucial momentum ahead of national elections later this year.
Mr Maliki, himself a Shiite with Islamist roots, campaigned on a rigorously non-sectarian law-and-order platform, even as his opponents adopted overtly religious slogans and images.
Saturday's provincial election was the most peaceful in Iraq since the fall of Saddam Hussein in 2003, and has been hailed as a sign of progress by Washington as its 140,000 troops prepare to leave.