Osong has arrived from Premier League side Nottingham Forest in search of regular game time.
Advertisement
Advertisement
The 19-year-old was involved with Forest’s B team in Premier League 2 last season.
Rotherham manager Steve Evans told the club website: "This has been a three-month-long process and we have had to show great patience but it will be worth the hard work put in.
"A striker who scores a goal is hard to get at any time and one who works so hard for the team is very rare, we have that with Esapa."