Mr Worachet was handed over by a military escort to the Crime Suppression Division about 10.20am. He declined to talk to the press on arriving at CSD headquarters.
Pol Col Prasopchoke Prommool, deputy CSD commander, said Mr Worachet would be formally charged at the CSD headquarters with defying the order by the National Council for Peace and Order (NCPO) to report to military officials.
The police would then take him to the Bangkok Military Court and request that he be ordered detained for another 12 days for interrogation.
Winyat Chartmontree, secretary-general of the Group of Volunteer Lawyers for Human Rights, said he had been asked by Mr Worachet's family to handle the case. He said he had prepared 20,000 baht as security to support a request for Mr Worachet's release on bail.
Mr Worachet was summoned to report to the NCPO on June 10. His wife went to see the NCPO instead, saying that Mr Worachet was sick.
Thira Suthiwarangkura, a law lecturer of Thammasat University and a member of the Nitirat group, on Wednesday morning posted on his Facebook page a denial that Mr Worachet had been arrested.
He said in a posting about noon on Monday that Mr Worachet returned to Thailand from Hong Kong through Don Mueang airport. He had accompanied Mr Worachet's wife and Col Songwit Noonpakdi to meet him at the airport.
"Dr Worachet was not arrested. He voluntarily reported to the army, following advance coordination. He was led by soldiers to report to the NCPO at the Army Club on Monday (June 16) after returning from Hong Kong," Mr Thira wrote.