"Our party legislators will vote for Pranab Mukherjee," JMM chief Shibu Soren told reporters here. JMM has 18 MLAs and three MPs from Jharkhand.
The announcement comes three days after Mukherjee met Soren at his residence here.
JMM has become the second non-Congress party after Babulal Marandi's Jharkhand Vikas Morcha (Prajatantric) to extend support to Mukherjee.
Junior ally in the BJP-led government, AJSU party has not yet decided on its choice of candidate. BJP is backing the candidature of former Lok Sabha speaker P A Sangma.