Isom will take up the role from 31 March 2022, when he will also join the airline’s board of directors. Parker will continue to serve as chairman of the board.
Isom, who was named president in 2016, brings more than 30 years of industry experience across finance, operations, planning, marketing, sales, alliances, pricing and revenue management.
Parker, who has worked with Isom for 20 years, said he was "incredibly pleased" that he will be the next chief of American Airlines.
"Robert is a collaborative leader with deep operational expertise and global industry experience," he added.
"His efforts to guide and support our team throughout the pandemic have been nothing short of phenomenal.
"We are well-positioned to take full advantage of our industry’s recovery, and now is the right time for a handoff we have planned and prepared for."
Isom said he was "humbled" to succeed Parker. "Over the past several years, our airline and our industry have gone through a period of transformative change," he added.
"And with change comes opportunity. Today, our more than 130,000 dedicated team members fly more people than any other US airline on the youngest fleet of all the network carriers, and we are positioned to continue to lead the industry as travel rebounds.
"I want to thank Doug for his partnership over the past two decades. He is a leader and teacher who inspires all around him and leaves an incredible legacy at American and in our industry."
