"Dialogue and discussions led to a vote and the choice of Mehdi Jomaa as the candidate for the post of head of government," said Houcine Abassi, secretary general of the powerful UGTT trade union, according to AFP.
"Our people have waited for a long time, but despite the difficulties and obstacles... this dialogue has not failed," he said, adding his "congratulations to Tunisia."
Of the 21 parties participating in the talks, only the Nidaa Tounes party rejected the choice and abstained in the vote.
According to a deal clinched between Tunisia's main parties in October, the new premier has 15 days to form his new government of independents.
He also faces the weighty task of organizing elections in 2014.
Jomaa, a relative unknown, is a 51-year-old engineer with no stated political affiliation. He is married and has five children.
He graduated from the National Engineering School of Tunis in 1988 before taking a higher degree in mechanics, his official biography published in March by state news agency TAP said.
He then went on to a career in the private sector, and headed a division of Hutchinson, the aerospace unit of French conglomerate Total.
He became industry minister following the formation in March of a new government by Ali Larayedh in the crisis that erupted following the assassination a month earlier of key opposition figure Chokri Belaid.
Since then, Jomaa has stayed aloof from the country's political jockeying and focused on his portfolio. In particular, he has lobbied European firms to invest in the country, plagued by economic woes since the ouster nearly three years ago of dictator Zine El Abidine Ben Ali.
But he has also taken the unpopular step of backing a decision to raise fuel prices next year.
Jomaa was chosen a day after the candidate agreed on by the outgoing Islamist-led government and the mostly secular opposition, 92-year-old Mustapha Filali, ruled himself out due to his age.
Ennahda has led a coalition government since the country, the birthplace of the so-called "Arab Spring", held its first ever democratic elections in October 2011.
HH/HH