It was the second reshuffle of the Yingluck cabinet, involving 23 posts.
At the swearing-in ceremony, which formalised the cabinet ministers' status, the appointees led by Ms Yingluck pledged loyalty to the monarch.
They also swore to be honest in conducting their ministerial duties for the good of the country and the people.
Deputy Prime Minister and Education Minister Phongthep Thepkanchana said the Royal Household Bureau informed the cabinet members beforehand that His Majesty the King would not speak at the oath-taking ceremony.
The new cabinet ministers will attend a special meeting at Government House today starting at 9am.
Meanwhile, 24 senators have requested a ruling on whether Varathep Rattanakorn is constitutionally fit to assume the post of PM's Office minister.
The senators made the request to the Constitution Court through Senate Speaker Nikhom Wairatpanich yesterday.
The senators, led by Prasarn Maruekapithak, said Varathep might not be qualified for the job because he was sentenced to two years' imprisonment by the Supreme Court's Criminal Division for Holders of Political Positions for malfeasance in connection with the two- and three-digit lottery while serving as a deputy finance minister in the Thaksin Shinawatra government.
Varathep was sentenced to two years in prison on Sept 30, 2010. However, the sentence was suspended for two years.
Mr Prasarn said Section 174(5) of the charter states a cabinet member must not have been sentenced to a term of imprisonment and he must not be appointed as a minister any sooner than five years after serving a sentence for a crime.
Mr Nikhom said he would have to first verify the signatures supporting the petition, a process which he said would not take very long, before forwarding it to the Constitution Court.
However, Kamol Bandaipech and Pichit Chuenban, who are in the Pheu Thai Party's legal team, insisted Varathep was qualified to take up the cabinet portfolio because he had not actually served a prison term.
They said it was required under the constitution that a person who is given a sentence of imprisonment must wait until five years after he has finished serving his or her sentence before he could assume a cabinet post.
This meant, they said, that the ban applies only to those who were physically imprisoned. Varathep, however, had not served any jail time.
Varathep said he was not worried about the petition. As long as the court has not passed a ruling on his status, he remains qualified to work as a minister.
The premier reiterated that Pheu Thai had thoroughly checked Varathep's qualifications before his appointment as a cabinet member.
She said she has complete confidence Varathep is in the clear.
But since the opposition wanted to pursue the matter, all the government could do was to wait and see how the court would rule, she said.