He previously represented Arizona in the U.S. Senate from 1995 through 2013.
Once he is formally installed in the Senate, Kyl's first major vote is likely to be on the confirmation of Brett Kavanaugh to the U.S. Supreme Court.
Former Senator Jon Kyl, R-Ariz., answers a question after Gov. Doug Ducey, R-Ariz., announced the appointment of Kyl to fill Sen.
"It's not the time for newcomers, and now is not the time for on-the-job training", Ducey said. As such, he'll be able to vote on Kavanaugh's nomination.
He would provide more of a cushion to a Republican victory in the deeply divided Senate given that McCain had been too sick all year to cast votes in Washington.
"The best piece of advice I received was from another governor who said, 'just do the right thing".
Bob Woodward, the Watergate veteran who set his sight on Donald Trump
Not strictly national security , but certainly indicative of a national emergency: Trump's lawyer told him, "Don't testify". Woodward concludes the call by saying "I believe in our country, and because you're our president, I wish you good luck".
Arizona law requires the governor to appoint a member of the same political party to fill a seat opened by the departure of a senator.
The appointment of Kyl will run through 2020, at which time a special election will determine who will fill the remainder of McCain's term, which ends in 2022.
"Hopefully he stays for two years", Ducey told KTAR News 92.3 FM's Mac & Gaydos a few hours after the appointment.
"I think sometimes, his desire to jump into the middle of a fight or maybe even create a fight - by the way, that reminds me of somebody - but sometimes, that can be detrimental to what he's trying to achieve", Kyl said, in what appeared to be a veiled comparison to McCain.
Democrats view the Arizona race as one of their best chances to flip a seat from red to blue, as they seek to take back control of the Senate.
"Our friend and former colleague Senator Jon Kyl is one of the most serious, most expert, and most effective legislators with whom I've had the pleasure of serving".
"There is no one more qualified and Arizona is well served", he said.
McCain died late last month at age 81 following a yearlong battle with brain cancer. Although Arizona has been a reliably Republican state, demographic trends have raised Democratic hopes of winning there in November and in future statewide elections.