Haryanto became Indonesia’s first Formula One driver in March. He started 12 races without scoring a point.
Ocon is backed by both Mercedes and Renault, where he was a reserve F1 driver, and will partner German rookie Pascal Wehrlein at Mercedes-powered Manor.
Manor, the smallest Formula One team but 10th of 11 in the current championship standings, signed Indianapolis 500 winner Alexander Rossi of the United States as their official reserve in March.
However, he said this month that he turned down an offer to race the rest of the season with them due to his IndyCar commitments.
“My management and I are in constant communications with Manor and we knew there might be an opportunity to race for the last half of the 2016 season,” he told Autosport.
“We gave it careful thought but declined the race seat due to my IndyCar contract.”
(Reporting by Alan Baldwin- Editing by John O’Brien)
