Jobseekers must use the DWP's own website or lose their benefit, Employment Minister Mark Hoban warned today.
Mr Hoban said he was making it compulsory to use its own Universal Jobmatch website.
"If someone refuses to use a service that already has 460,000 employers posting jobs, you have to ask why," he said.
But jobseekers still had every right to refuse to let the DWP plant "cookies" - code that tracks a user's online activity - on their computers, advocacy website Consent.me.uk said.
PCS union said Jobcentre staff had "very serious concerns" given the website's bugs and scam advertisements.
A government guided by common sense would respond to news that publicly owned Royal Mail has increased profits to £403 million by scrapping plans to flog off the service.