He was confirmed on Wednesday after screening by Senators, to succeed Justice Walter Onnoghen, who resigned following some false asset declaration.
The confirmation followed a two-hour question and answer session between the senators and Mohammed, who had been in acting capacity as CJN since January.
President of the Senate, Dr Ahmad Lawan announced the confirmation after a voice vote at plenary on Wednesday.
Mohammed who entered the National Assembly complex at exactly 10:10 a.m., went into closed-door session with the lawmakers at 11:13 a.m. and left by 1.06p.m.
The Senate, contrary to the earlier promise that they would screen him in the open plenary, retired into an executive session to do so.
President Muhammadu Buhari last week, requested the confirmation of Mohammad as the substantive Chief Justice of Nigeria, following the recommendation of the National Judicial Council (NJC).
Justice Mohammed was first appointed in January after Buhari suspended Chief Justice Walter Onnoghen.
The new CJN provided answers to questions from the senators in areas like financial autonomy of the judiciary, concept of imprisonment and corruption in the judiciary.
He also spoke on the concept of individualism and collectivism in administration of justice as it affects criminal matters.
Muhammad spoke extensively on the roles expected of the parliament in addressing alleged rot in the judiciary.
He urged National Assembly and states Houses of Assembly to review the criminal laws in the country to effectively fight corruption.
“Nigerian judiciary is part of the Nigerian system. Therefore, I’m not surprised if some judges are corrupt, that doesn’t mean that those judges should not be identified and dealt with.
“The most worrisome of it is that it happens at the lowest ebb of the courts. This is where the main problem arises.
“Let me say generally that that corruption is inherent in the person who is corrupt and the person who is corrupted. But all of them should be made to face the music.
“I therefore urge the National Assembly and the state House of assembly to take a look at our criminal laws.
“The parliament should sanitise the society. Much as we in the judiciary want to do that, the parliament should make new laws and amend old ones,” he said.
On judicial autonomy, he said: ” We have started seeing the autonomy. But go to some states, the judiciary is still refused ordinary monthly grants to run its offices.
“It is the duty of the legislature to touch these places. To close all ends and identify all people being corrupted.
“It is my view that it is only the legislature that can put things right.I can’t go and ask or beg anybody for anything, I’m contented with what I have.”
Later in his remarks, Lawan thanked the CJN for coming to answer some questions from the Senate.
He also promised him that the 9th Senate would ensure a harmonious relationship with the judiciary.
“My Lord, thank you for coming to answer questions from members of the Senate. We are all ready to work with the judiciary.
“We must ensure that the judiciary is properly funded and remunerated. If we are asking them to live above board. We should do the right thing,” he said.