Kovan, who had earlier been arrested by the state government on similar charges, and 57 others, were held for protesting near the Shastri Bhavan, housing central government offices, police said.
The protestors, who raised slogans against the BJP-led government at Centre, demanded the release of Kumar, they said.
Kovan was arrested last year under sedition for allegedly insulting Chief Minister J Jayalalithaa in a song in his campaign against the state government's liquor policy.
House Circle, also included members from various political youth outfits and student bodies, such as NSUI, AISF, AIYF, some of whom rode in cantors, waving their flags and raising slogans in support of JNU and Kanhaiya.
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The members also condemned the attack on the arrested JNUSU president and students and media in Patiala House court complex earlier this week.
And as the massive crowd, which lined one side of the almost entire Barakhamba Road from Mandi House, marched on way to Jantar Mantar, slogans like 'Long Live JNU' and 'Stop media trial of JNU' rent the air.
While a Vajra vehicle was seen stationed at the Mandi House Circle at the start of the protest, some police officials and personnel were monitoring the movement of the crowd, which marched vociferously but peacefully.
Senior journalist P Sainath, theatre and film personality M K Raina, actress Swara Bhaskar, former NSD director Anuradha Kapur, well-known photographer Ram Rahman and a host of other academicians also joined the protest.
Janhastakshep condemning the attack in Patiala House court premises by lawyers on media and supporters of Kanhaiya alleged, "It is remarkable that the state machinery not only failed to prevent the occurrence of this violence, but seemed to be complicit in it."
As the crowd wended its way to Jantar Mantar, where the protesters later gathered, a student, on the sidelines, was seen carrying a copy of the preface of the Constitution, lending a sense of poignancy to the agitation.
Ruchika, 20, a student of Ambedkar University Delhi, who had come to the protest site along with 50-60 other students from her university, said, "Patriotism and nationalism have been reduced to such small definitions by right-wing forces. And also even if one were to assume that if somebody objects to speeches made by a few people, then the criticism should remain focussed and not taken to gross generalisations."