They were among 20 fourth-year geological engineering students who trekked to study rocks in the national park.
Jaranya Thong-ngam, head of Ban Suan Hom in Wang Nam Khieo district, said about 100 rescue workers, park rangers, police and villagers entered the thick forest in search of the missing students on Monday evening.
The forest is home to many dangerous wild animals.
Although rescuers could contact them via mobile phones, it took about two hours to reach the six exhausted students, who were found about three kilometres inside the national park.
Tantikorn Kromwangkoi, one of the lost students, said they decided to trek in the forest in groups of 6-7 students to study local rock formations during their school holiday.
His group had a map of the forest and a global positioning system but miscalculated the distance to the park exit, so they could not make it out before nightfall and became lost.
The rescue took about eight hours as searchers had to carry Mr Tantikorn, who weighs nearly 100 kilogrammes and was too exhausted to walk out of the forest.