In a letter addressed to Station House Officer of Civil Lines Police Station, the chief minister said he would be available at 5 pm on Friday at his camp office. The police had yesterday sent him a notice to join the investigation on Friday at 11 am.
Mr Kejriwal also informed the police that he will video record the proceedings.
He wrote to the police that if they have issues with him video recording the proceedings, they can make arrangements and provide him the video after the questioning is over, the police said.
Mr Prakash was allegedly assaulted during a meeting at Mr Kejriwal's official residence on February 19.
Police have already questioned the 11 Aam Aadmi Party MLAs, who were present at the chief minister's residence for the meeting. Two MLAs Amantullah Khan and Prakash Jarwal were arrested in the case.
On February 23, a police team had examined the CCTV system installed at the chief minister's residence in the Civil Lines area and seized the hard disk. The forensic report on the hard disk is still awaited.
The "conspiracy" of assault on Mr Prakash was "hatched" at Arvind Kejriwal's residence so it was no surprise that he would be questioned by the police, alleged Vijender Gupta, BJP legislator and Leader of Opposition in the Delhi Assembly.
"The chief minister should cooperate in investigation instead of indulging in politics over it," Mr Gupta said.
The alleged assault on the chief secretary had triggered a bitter tussle between the Delhi government and its bureaucracy.