The CCSA reached the decision during a meeting chaired by Prime Minister General Prayut Chan-o-cha.
The lifting of the orange status of the 20 provinces increased the number of provinces under high surveillance for Covid from 47 to 65.
Two of the 47 highly-monitored yellow provinces were elevated to blue, or pilot tourism provinces, raising the number of blue provinces to 12.
The 12 blue-zone provinces are: Bangkok, Kanchanaburi, Krabi, Chonburi, Chiang Mai, Nonthaburi, Pathum Thani, Phang Nga, Phetchaburi, Phuket, Rayong and Songkhla.
The CCSA added that some districts of the four yellow-zone provinces are categorised as blue.