All lawyers obtaining or renewing their professional licence will have to pledge their loyalty to the country and the leadership of the party.
Critics see the move as lacking legal basis and ”inappropriate”.
The oath was necessary to raise lawyers’ political, professional and moral standards, said the ministry.
It has also named institutions to organise the oath-taking ceremonies and specified that lawyers need to take the pledge within three months from the date on their certificates, state media Xinhua news agency reported.
The new requirement comes at a sensitive time of political transition, with the Communist Party preparing for a once-in-a-decade leadership transfer later this year.
In recent years, the Chinese authorities have increased pressure on lawyers who take on politically sensitive cases.
“As a lawyer, you should only pay attention to the law and be faithful to your client,” another well-known rights lawyer, Mo Shaoping told Reuters news agency.
“The oath will hurt the development of the Chinese legal system.”