DOJ spokesperson Kerri Kupec confirmed Ohr's resignation in a statement, saying he retired on Sept. 30 "after his counsel was informed that a final decision on a disciplinary review being conducted by Department senior career officials was imminent."
CBS News first reported the news of Ohr's resignation.
Horowitz found that Ohr acted improperly in not keeping department leadership or his supervisors in the loop about his meetings with FBI officials and others as he engaged them about a series of salacious allegations tying Trump to Russian operatives featured in a "dossier" compiled by Steele.
Horowitz admonished Ohr for what he described as "consequential errors in judgment." Though he also concluded that Ohr was not required under ethics rules to consult with the department counsel before working on the Russia investigation even though his wife Nellie Ohr was at the time employed by Fusion GPS, the research firm that first hired Steele to look into Trump's ties to Russia.
ABC News reported previously that Ohr's interactions with FBI officials on the dossier had little impact on the bureau's growing investigation into Trump and his associates' ties to Russia, and Horowitz's review separately determined the probe was properly launched.
Even as Ohr continued working at the department, Trump repeatedly assailed him and his wife as among those responsible for a political "witch hunt" targeting his campaign, even threatening to strip Ohr of his security clearance.
A lawyer for Ohr declined to comment when reached by ABC News.
ABC News' Mike Levine contributed to this report.