His wife Assoc Prof Naraporn Chan-ocha, members of the NCPO and permanent secretaries of ministries attended the ceremony.
Pornpetch Wichitcholchai, president of the National Legislative Assembly, presented the royal command.
Gen Prayuth said that he will propose his cabinet line-up to His Majesty the King within September.
He promised to solve national problems urgently and to be accountable.
Gen Prayuth vowed to tackle corruption, especially that in the government sector, and to develop the nation in all dimensions.
He asked general public to support the work of his government.
The nation's economic problems would be solved quickly and sustainably to prepare Thailand for the ASEAN Community, he pledged.
He promised to work for the national interest and with honesty, and promote national unity.