"I am leaving the post of prime minister this evening with a feeling of accomplishment," Lamothe said in a televised address, Haiti's communication ministry tweeted from its official account.
President Michel Martelly, who is also targeted by the demonstrators, announced on Friday that Lamothe was ready to go to help resolve a political impasse that has meant that parliamentary elections have been postponed for the last three years.
On Saturday one man was shot dead during protests calling for Lamothe’s and Martelly’s resignation in Port-au-Prince.
Hundreds of youths tried to break through police cordons to enter the presidential palace.
An advisory commission set up by Martelly last week recommended that Lamothe resign and that a coalition government, including the opposition, be formed.
It also recommended disbanding Haiti’s electoral council with a view to holding parliamentary and municipal elections and freeing political prisoners.