The chief minister-designate has invited Mr Modi to his swearing in ceremony on Saturday, reports say.
The Aam Aadmi Party leader will be sworn in at the Ramlila grounds, and not in the assembly as is tradition.
The AAP won 67 of 70 assembly seats, relegating Mr Modi’s BJP party to a poor second position with three seats.
The results came as a huge setback for Prime Minister Narendra Modi, who led his Bharatiya Janata Party (BJP) to victory in last May’s general election.
He has enjoyed huge popularity since taking office, winning a string of local elections and wooing international investors and world leaders.
Mr Kejriwal and his senior party colleague Manish Sisodia called on Mr Modi at his home in Delhi on Thursday morning and invited the prime minister to his swearing in ceremony.
“The prime minister said he would not be able to come,” Mr Sisodia told reporters after the meeting.