Hansen himself revealed his appointment to Periscope, which lets users broadcast live video free of charge from smartphones running Android or Apple iOS software. The videos remain available for 24 hours before disappearing.
"I am joining Periscope as editor in chief," he wrote in a farewell blog on story-sharing site Medium where he is an editor.
"I still love the written word and Medium but I honestly can't think of many things more interesting than helping build a new platform with mobile phones and real time video," he wrote late Monday.
Hansen, who was editor in chief of technology news site Wired before he joined Medium, said he would start on May 16 at Periscope, which last week boasted that more than 200 million broadcasts had been created on its platform since it was launched a year ago.
In an interview with CNNMoney, Hansen said the role would involve developing the site and "surfacing the most interesting content to the people most likely to want to see it."
Periscope faces a challenge from Facebook's Live video streaming feature, which was launched in mid-2015.
In its job advertisement, Periscope said the editor in chief would establish a global editorial team to discover and highlight the most important, newsworthy and entertaining content.