The official count was 1,232 votes for Malloy to 582 votes for Lamont.
"It's an honor to have the support of som many hard working Democrats," said Malloy in a prepared statement. "Together, we're prepared to put Connecticut back to work, to fix what's broken in state government and to bring real and lasting change this November."
This is the second time in four years that Malloy has won the party's endorsement for Governor.
Lamont's votes qualify him to force a primary in August.