He notified Gov. Phil Murphy of his decision in a letter sent on Tuesday.
Menendez said the August date will "give time for my staff to transition to other possibilities, transfer constituent files that are pending, allow for an orderly process to choose an interim replacement, and for me to close out my Senate affairs."
Menendez said Tuesday he fully intends to appeal the jury's verdict all the way to the Supreme Court and did not want the Senate to be involved in a lengthy process that will "detract from its important work."
"Furthermore, I cannot preserve my rights upon a successful appeal, because factual matters before the ethics committee are not privileged. This is evidenced by my Committee's Staff Director and Chief Council being called to testify at my trial," Menendez wrote.
It will be up to Gov. Murphy to name an interim replacement. An election for Menendez's seat will be held in November.
Democratic Congressman Andy Kim and Republican developer Curtis Bashaw are on the ballot. Menendez will be on the ballot following his decision earlier this year to run as an independent.
A Manhattan federal jury found the New Jersey Democrat guilty on all charges, including bribery, fraud, acting as a foreign agent and obstruction, on Tuesday following a two-month-long trial. Federal prosecutors said he accepted hundreds of thousands of dollars in bribes in the form of cash, gold bars, mortgage payments and more in exchange for the senator's political clout.
Menendez was not required to resign due to the conviction. He is scheduled to be sentenced on Oct. 29 and faces decades in prison.
Following the guilty verdict, several political leaders called for Menendez's immediate resignation, including Majority Leader Sen. Chuck Schumer, D-N.Y.
"In light of this guilty verdict, Senator Menendez must now do what is right for his constituents, the Senate, and our country, and resign," Schumer said at the time.
Sen. Cory Booker, Menendez's New Jersey counterpart, and Murphy had also joined in the calls for his immediate resignation. Murphy said at the time that he would call on the U.S. Senate to expel him if the senator refused to resign and make a temporary appointment in the event of a vacancy.
Following the verdict, he vowed to appeal his conviction. He told reporters he was "deeply disappointed" by the jury's decision while maintaining his innocence.
"I have never violated my oath," Menendez said outside the courthouse following the verdict. "I have never been anything but a patriot of my country and for my country. I have never, ever been a foreign agent."
He added that the jury's decision would "put at risk every member of the United States Senate in terms of what they think a foreign agent would be."
Menendez, who served as senator for New Jersey since 2006, became the first sitting member of Congress to be charged with conspiracy by a public official to act as a foreign agent.
He refused to resign following the initial indictment in September 2023 despite calls from a majority of Democrats to do so, though he did step down as the chairman of the powerful Senate Foreign Relations Committee.
In June, he filed a petition to get on the U.S. Senate ballot in New Jersey as an independent candidate.