Workers claim the reforms will lead to corporate exploitation and erode their hard-won rights.
The world’s fifth-largest economy recently implemented long-awaited labor laws replacing colonial-era legislation.
The overhaul consolidates 29 existing labor laws into four key codes, cutting rules from over 1,400 to about 350.
Gautam Mody from the New Trade Union Initiative said workers from all sectors protested outside factories and city centres.
“Workers have been blindsided by the government,” he told AFP.
“We want fairness, justice and equity before the law which are being denied under the new codes,” Mody said.
While new regulations boost safety standards and mandate social security for gig workers, they also allow longer factory shifts.
The reforms make it tougher for workers to conduct strikes and easier for medium-sized firms to fire employees.
A controversial provision raises the threshold for firms needing government permission for layoffs from 100 to 300 workers.
This means companies with up to 300 employees can retrench staff without approval.
Trade unions aligned with parties opposed to Prime Minister Narendra Modi have called it a “deceptive fraud”.
The Centre of Indian Trade Unions said the codes constitute “the most sweeping and aggressive abrogation of workers’ hard-won rights”.
Modi has described the changes as “one of the most comprehensive and progressive labor-oriented reforms since Independence”.
India remains the world’s fastest-growing major economy but faces slowing growth.
Analysts at Nomura said the reform attempts to modernize “arcane and compliance-intensive labor laws”.
They noted it’s part of a broader trend to hasten economic reforms following recent Trump tariffs.