More than 60 professional runners participated in the race, while several hundred enthusiasts ran in other cities on routes of their choice, using a mobile app to post race timings, said the event organisers.
Although air quality was poor on Sunday, the runners got a bit of a reprieve, as pollution levels in the capital were dramatically better than those of recent weeks.
New Delhi's Air Quality Index was at 252 on a scale of 500, registering at "poor" levels, according to the Central Pollution Control Board. But skies were relatively clear and the readings were significantly below the "severe" levels as high as 488 recorded earlier this month.
The race was scaled back as the city experiences a third wave of the pandemic.
"Organisers are not inviting general runners at the stadium like every year to avoid a big gathering," an event official said, adding that hundreds of amateur runners were running in other cities after registering through an app.
Defending champions from Ethiopia, Andamlak Belihu and Tsehay Gemechu, were among the elite athletes running the 21-kilometre (13.1 mile) race.
The Airtel Delhi Half Marathon 2020 "is a very significant moment for Indian sports since the pandemic began," said Abhinav Bindra, brand ambassador of the event and India's only individual Olympic gold medallist.
The event is a step toward resuming competitive sports in India and would be a benchmark for other sports to follow, he said.
"The Airtel Delhi Half Marathon will follow the highest level of safety standards, with bio-secure zones to ensure a COVID free race for the elite runners," the organisers had said in a press statement earlier.
The race also took place as thousands of farmers, riled by new agricultural laws, staged a third straight day of protests, blockading some arterial roads into the capital.
