His arrest took place hours after the Bihar police picked up his brother for questioning.
Sharjeel Imam will be brought to Delhi after which his questioning will begin, sources said. His family, sources said, has denied the allegations of sedition, saying his comments were taken out of context. Appearing before the media earlier today, his mother said he was "not a law-breaker and would surrender to the investigating agencies".
"Nobody should do anything that is not in the interest of the nation. The accusations and the arrest - the court will decide on the matter," Bihar Chief Minister Nitish Kumar was quoted as saying by news agency ANI after the arrest.
A sedition case was registered against Sharjeel Imam in Delhi for his alleged call to sever the whole of the northeast from the rest of India after the imposition of the Citizenship Amendment Act or CAA. He is also wanted in other states, including Assam, Manipur, Arunachal Pradesh and Uttar Pradesh.
By last evening, the hunt for him had spread to Mumbai, Patna and Delhi as the Delhi Police pushed in five teams from its Crime Branch.
The Delhi police claimed he made divisive speeches on two occasions, once at the Jamia Millia Islamia University at the height of the anti-Citizenship Amendment Act protests in December, the other at the Aligarh Muslim University in Uttar Pradesh, another epicentre of the protests against the Citizenship Amendment Act or CAA.
Sharjeel Imam is allegedly one of the organisers of the protest at Delhi's Shaheen Bagh protest. But the protesters at Shaheen Bagh distanced themselves from his comments, saying that "no single person" can be called the organiser. His mother said he was in favour of "calling off" the agitation.
The Citizenship Amendment Act makes religion, for the first time, the test of Indian citizenship. The government says it will help non-Muslim refugees from three Muslim-dominated neighbouring countries if they fled to India because of religious persecution.
Critics say the bill discriminates against Muslims and violates secular tenets of the Constitution.