The announcement comes just as reports have suggested Google would make such a move.
Here's what Horowitz wrote in his post:
Just wanted to confirm that the rumors are true -- I'm excited to be running Google's Photos and Streams products! It's important to me that these changes are properly understood to be positive improvements to both our products and how they reach users.
Rumors that Google would break up its social network have been circulating for almost a year since Vic Gundotra, who previously oversaw Google+, announced he was leaving the company last April.
Horowitz's post also confirms reports we've heard from Bloomberg and TechCrunch over the last several months. Sundar Pichai, Google's senior vice president of Chrome, Android, and apps, hinted as much when speaking to Forbes last week.
"I think increasingly you'll see us focus on communications, photos and the Google+ Stream as three important areas, rather than being thought of as one area," Pichai said to Forbes.
The move isn't necessarily surprising either. Over the course of its four years of existence, Google+ hasn't really proven to be as popular as platforms like Facebook. It serves more as a means of keeping you logged into your Google account when using the Chrome browser.
Google+'s photo platform has proven to be pretty useful for those who actually use it, though, which means it has a chance at succeeding as a standalone product. Google+ stores all of your photos in virtual albums that are automatically organized and edited by Google's algorithms, as Business Insider's Steve Kovach pointed out.