The UAE strike late to keep their World Cup hopes alive
The UAE were seconds from dropping out of the running for Russia 2018 when Mabkhout scored from close range after a knockdown in the third minute of added time.
It means UAE are mathematically capable of securing third place in Group B and a play-off spot, but they need big wins in their last two games and for other results to go their way.
A quiet first half picked up after the break when Thailand's Mongkol Thossakrai scored from close range in the 69th minute, unleashing huge roars at a packed Rajamangala Stadium.
UAE, inspired by Asian player of the year Omar Abdulrahman, fought back hard but they were unable to breach the War Elephants' defence until Mabkhout's late sucker-punch.
Failure to beat bottom-placed Thailand -- after their 3-1 victory at home in October -- is a blow for UAE, a rising star of Asian football and host of the next Asian Cup in 2019.
Former Argentina coach Edgardo Bauza took charge of the team in May, while Thailand also were also under new management after hiring Serbian Milovan Rajevac in April.