Only 38 MPs were present for the vote, which took place hours before the state of emergency was due to expire, despite 43 lawmakers being needed for the vote to take place as required by the constitution, Maldives Independent news website reported.
All 38 were from the ruling party and all 38 approved the extension, it said. The opposition had boycotted the vote.
The state of emergency will now end on March 22.
Parliament Speaker Abdulla Maseeh quoted parliamentary regulations which do not include state of emergency declarations among the votes where a constitutionally required quorum is needed.
Under the emergency law, Yameen had two Supreme Court judges arrested, accusing them of corruption. Later, the remaining three judges annulled the order to release Yameen's opponents.
There has been international condemnation of the government's moves, with the US and India expressing concern.
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