In an internal communication sent to all of its employees in Malaysia, the company said that 54-year-old Karamjit Singh, who was on a rotational assignment to Nigeria, had been on the flight.
"Karamjit was with the SHE Department before accepting a rotational assignment in April 2013 with Esso E & P Nigeria as an OIMS and Safety advisor on the USAN FPSO south of Port Harcourt," the email said, referring to the Safety, Health and Environment deparment in the organisation.
Karamjit, who is a father of two boys, had just finished his rotational shift and was on his way home to Kuala Lumpur.
"He was a dedicated and long-serving employee with 29 years of service with Exxon Mobil."
Karamjit, the company said, was a "dear friend, colleague, and brother" to many and would be "deeply missed".
"Our thoughts and prayers are with them (his family) and other families of MH17 passengers as they go through this difficult time," it said.
The Malaysia Airlines plane was believed to have been brought down by a missile fired by pro-Russian rebels fighting the Ukrainian forces.
The Malaysian Airlines Boeing 777 jetliner was flying from Amsterdam to Kuala Lumpur, when it came down near the city of Donetsk, a stronghold of pro-Russian rebel forces.
The plane disappeared from the Ukrainian flight radar at 10.15pm local time and reports of an air crash in Ukraine began to surface shortly after.