Hirschhorn, an MTV Networks and Sling Media veteran, had been at MySpace for just over a year, having previously served as chief product officer.
"Yes i am moving back to NYC. Concrete jungle where dreams are made of. I believe in MySpace, its leader Jonesy and its wonderful team," Hirschhorn tweeted. He was referring to Mike Jones, who with Hirschhorn took over the co-presidency at News Corp.-owned MySpace in February after CEO Owen Van Natta stepped down. (The other sentence of the tweet is a lyric from the Jay-Z song "Empire State of Mind.")
There's no hint whether Hirschhorn may have a new role at another company lined up, but he's moving back to New York after relocating to the Los Angeles area for the MySpace job.
Jones had served as an AOL executive before joining MySpace as chief operating officer at the same time that MySpace first hired Hirschhorn.
News Corp. Chief Digital Officer Jonathan Miller followed up with a formal, though personal, statement.
"We fully respect Jason's decision to leave and his personal desire to return to New York," the statement read. "As many people know, Jason is like family to me, and as expected, he's done everything we asked of him and more. We're incredibly grateful for the passion and enthusiasm he brought to the company. And as I know Jason agrees, Mike Jones has done an outstanding job leading MySpace into its next evolution and is the right person to take the reins. There are no plans to bring in additional management."
Still, none of this is good news for MySpace, which has been going through one executive shake-up after another for the past few years. Van Natta quit after less than a year at the company, following the departure of co-founder Chris DeWolfe.
Meanwhile, MySpace has entirely lost the race for social-networking domination to Facebook. Attempts to shift its focus to music and pop culture have been ambitious but so far without major success or profits.