In the US-style primary, Agarwal defeated former legislator Rajesh Lilothia. Out of 299 party workers, 252 voted for Agarwal while the rest voted for Lilothia.
Agarwal said he was happy to win the primary and praised party vice president Rahul Gandhi for introducing the process in Delhi.
The primary was the brainchild of Gandhi. It is scheduled on an experimental basis in 16 constituencies countrywide - including two in Delhi - in which party workers would elect the candidate to contest the Lok Sabha polls.
Lilothia said he was happy to contest against a leader like Agarwal and the idea of primaries would strengthen democracy more.