The 22-year-old singer, who left the boy band earlier this year, took to Twitter to praise the group's new single "Drag Me Down", reported Entertainment Weekly.
"Proud of my boys the new single is sick... Big love," he tweeted.
"Drag Me Down" marks the band's first single as a foursome after Malik's exit.
Recently, the "What makes you beautiful" singer signed a solo contract with RCA and said he was waiting for this opportunity to explain why he left the band.
"I guess I never explained why I left... It was for this moment to be given the opportunity to show you who I really am! #RealMusic #RCA," he tweeted.