The stars dated for around four years in the late 1990s and are parents to a son named Seven, and their split inspired Andre to pen the OutKast track Ms. Jackson about their break-up.
They remained on speaking terms for the sake of their boy, now 18, but they surprised fans last month (Dec15) by teaming up in the studio again for Hello, a duet for Erykah's But U Cain't Use My Phone project, which features the soul star's take on a slew of phone-centric tunes.
"Our son Seven and I were trying to figure out songs that could help her - songs that were related to the subject of the mixtape: phones," Andre explains to Billboard.com. "We came across (The Isley Brothers' 1974 cover of Todd Rundgren's) Hello, It's Me.
"I told Erykah, 'You should make this into a new song and get somebody to rap on it.' She was like, 'Well, you should rap on it!' I'm happy it happened. It was a great reunion, because I don't think people have heard a song from us in ages."
The former couple last appeared on song together on OutKast's Humble Mumble, from their 2000 album Stankonia.
Meanwhile, Andre, who has been focused on his acting career of late, also revealed he is planning to share some new material of his own sooner rather than later.
"I still get time to think about music," he says. "(Shooting TV and film projects) is not so bad - it kind of puts you in the place where you're fiending to do music. I've been holding (back) for a long time, so now I'm really interested in figuring out some type of music to do. I'm always recording."
His last solo work, The Love Below, was released as part of a double OutKast album in 2003.