The comedian turned activist endorsed Lucas after interviewing her for his YouTube series, The Trews.
He told Lucas: "People that live in Brighton Pavilion should definitely vote for you." Turning to the camera, he added: "Are you a person that lives in Brighton Pavilion? If you are, you should definitely vote for this person, Caroline Lucas."
This contradicts Brand's previous position that voting is pointless and people shouldn't bother with it. In 2013 he wrote in the New Statesman: "I will never vote and I don't think you should, either."
Lucas is a former Green party leader who was elected as its first MP in 2010 and is fighting for re-election in the Brighton seat. Brand said she and current leader Natalie Bennett were "obviously decent people".
He added: "It's like the opposite of what I imagine it's like to meet David Cameron and what I know it's like to meet Nigel Farage – people who are working for the unelected interests that control this country."
Brand wasn't so kind about Ed Miliband after their interview earlier this week.
Miliband received some flak for agreeing to be interviewed by someone who had urged people not to vote.
But the Labour leader said he was trying to reach out to people who weren't interested in the election.
Emily Ashton is a senior political correspondent for BuzzFeed News and is based in London.
Contact Emily Ashton at firstname.lastname@example.org.
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