The resignation will effect Tuesday, and Herzog will begin his new job as chairman of the Jewish Agency on Wednesday.
Herzog will wrap up 15 years in the Knesset, in which he has served five terms. He will be replaced as opposition leader by Tzipi Livni and as an MK by the next name on the Zionist Union list, former Kadima MK Robert Tiviaev.
Livni's appointment will need to be approved by the MKs in the opposition the next time the Knesset convenes.
Signatures have been drafted to force a special session of the Knesset during its summer recess on the Jewish Nation-State Law and the Surrogacy Law. Livni is expected to deliver her maiden address as opposition leader at that session.
Tiviaev will be sworn in at the Knesset session. He has said that if elections would be held now, he would not vote for the Zionist Union.