The proposed "Comcast Innovation and Technology Center" will be located on the 1800 block of Arch Street in Center City.
When finished, the tower will be 59 stories tall at a height of 1,121 feet and will be located next to the Comcast Center, which stands 975 feet tall and opened in June 2008.
Comcast said the building will become "a dedicated home for the company's growing workforce of technologists, engineers, and software architects."
"We continue to be proud to call Philadelphia our home, and are thrilled to build a world-class media, technology and innovation center right in the heart of the city," Comcast chairman and chief executive Brian L. Roberts said in a statement. "We have assembled an incredible design and development team to expand our vertical campus, and I am more excited than ever about the future of Comcast in Philadelphia."
The building was designed by Lord Norman Foster and will be developed by Liberty Property Trust.
and will include a Four Seasons hotel and a block-long lobby with a glass-enclosed indoor plaza that will offset the Comcast Center's outdoor plaza.
The lobby will feature a restaurant and a new concourse will provide direct connections with the Southeastern Pennsylvania Transportation Authority's regional commuter train hub, Suburban Station.
Though it will be the tallest building in Philadelphia, the new tower would be the 34th tallest building worldwide when complete, just seven feet shy of the 1,128-foot John Hancock Tower in Chicago and nine feet taller than Moscow's Mercury City Tower, according to the Council on Tall Buildings and Urban Habitat.
The tallest building in the U.S. is the Willis Tower in Chicago, which stands 1,451 feet. The world's tallest building is the Burj Khalifa in Dubai at 2,717 feet.
The Associated Press contributed to this report.