Jin Air, T'way Air, Air Busan, Air Seoul, Fly Gangwon and Air Premia will offer the discounts on flights from South Korea's major cities Busan, Daegu, Jeju and Incheon to Hanoi, Ho Chi Minh City, Nha Trang and Da Nang until the end of this month.
A representative of the Korea National Administration of Tourism in Vietnam said the move aims to encourage Vietnamese tourists to return to South Korea after reopening.
Since reopening in June, South Korea received 100,000 Vietnamese visitors.
More than 600,000 South Koreans came to Vietnam in the first 10 months this year, the highest of any nationality.
Before the pandemic, Vietnam welcomed nearly 4.3 million South Korean tourists in 2019, accounting for a fourth of all foreign arrivals.
Vietnam grants South Korean tourists 15-day visa exemption.