New flights will get under way on Friday (14 June), which Qatar says demonstrates its commitment to, and confidence in, the UK market.
The route launched in April 2003 and went double-daily in February 2011. The move to triple-daily will increase capacity 35%.
Onwards connections from Doha include Bangkok, Perth, Bali, Male and Kuala Lumpur.
Gary Kershaw, Qatar Airways country manager UK and Ireland, said: “Since launching in 2011, Manchester has performed exceptionally well, proving to be one of our most successful UK routes.
The demand from our customers meant it was only a matter of time before we increased our flight frequency.”
