Armstrong himself hired Gowrappan in April, and the move to make him CEO was expected. Gowrappan will report directly to Verizon CEO Hans Vestberg. Armstrong, meanwhile, will guide the Verizon's subsidiary's management transition efforts as a strategic advisor before leaving the company by the end of this year.
Armstrong will also report to former Verizon CEO and now chairman Lowell McAdam.
Oath includes AOL and Yahoo, which Verizon purchased for a combined $9 billion. Armstrong was initially tasked with welding parts from each of those companies into an advertising platform to rival the so-called duopoly of Google and Facebook. But the plan fell apart after parent company Verizon tapped Vestberg to lead its company following McAdam's departure.
Vestberg, an ex-Ericsson exec, sees the future of the company with 5G, not media, according to a senior level executive who asked to remain anonymous. The executive said that prompted Armstrong's decision to leave.
The executive added that others joined Oath under the assumption that Armstrong would remain CEO amd that some employees are now leaving as a result of his departure.
Meanwhile, Oath says its integration of AOL and Yahoo is complete, adding that Gowrappan, who joined Oath from Alibaba, will lead "the next phase of Oath's global growth strategy."
In the company's second quarter earnings call, it said that Oath generated revenue of nearly $4 billion during the first half, which was flat with the prior year.
"Guru has proven experience in scaling businesses globally," Vestberg said in a statement. "I'm thrilled he will lead Oath in an exciting new phase of growth, building on the foundation Tim and his team have created by delivering brands our customer love."