Ms Lucas gained the Brighton Pavilion constituency from Labour where the Greens had run a targeted campaign.
Speaking after the result was announced she said: "Today the people of Brighton Pavilion have made history by electing Britain's first Green MP to Westminster.
"Thank you so much for putting the politics of hope above the politics of fear and I pledge that I will do my very best to do you proud.
"For once the word historic fits the bill."
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