The company says Syncrude completed repairs and startup activities over the weekend to begin shipping product by pipeline.
The fire burned for two days in March at the Mildred Lake oilsands upgrader after a pipeline began leaking near one of its two hydrotreating units.
The plant can produce about 350,000 barrels per day when it is operating at capacity.
Shipments are currently at approximately 140,000 barrels per day and are expected to ramp up as additional units complete turnaround activities.
Suncor, which owns more than 53 per cent of Syncrude, says production is expected to return to full rates in June.
Note to readers: This is a corrected story. A previous version said Suncor completed the repairs and startup activities for the Syncrude Mildred Lake oilsands operation.