Mike Crockart said he was staggered to be told he would need to pay back £754, including interest, after successfully applying under the pseudonym for the three-month loan from QuickQuid.
The Edinburgh West MP told the Commons that he been responding to an unsolicited text message sent by another firm, which linked him to QuickQuid.
He made an initial application under his own name which despite not completing it led to a bombardment of messages about an approved payday loan.
To test whether proper checks were carried out, Mr Crockart repeated the process under the fake name and was successful.
He said there were nine texts on his phone directing him to a website offering payday loans.
He filled in the details asking for a £200 loan over a month period, and pressed the button 'get to your cash' - not apply, get your cash - expecting to be quoted a £50 charge, as advertised on the payday lender site, as an example loan.
"Instead, I found myself directed to the QuickQuid website. I was offered £400 over three months, with a total cost of £754 to pay back.
"I left it at that because I didn't think it was a good deal - I didn't even press any buttons on that second website, but I then received emails and texts."
Mr Crockart said he received messages saying "one more step to go", and half an hour later another urged him to sign the contract.
Some 15 minutes later a call came from America urging him to sign up, he said.
After 20 minutes an email with pre-contract information arrived, followed by several emails warning his application was about to expire. And he added: "That was worrying enough, but I thought, is this website just a front for QuickQuid?
"So I went in again but this time I made up details, I called myself Boris Peep. I made a further application.
"It was a made-up name, I put my constituency address as the address for the application and immediately started getting other texts saying 'Hi Boris, your application has been approved'.
"A made-up person ended up being approved for payday loans.
"It is very, very worrying and needs urgent action."
The chairman of the Commons Culture Select Committee, John Whittingdale, said while nuisance calls through cold calling were a real issue for households, he warned against a total ban of cold calls, saying there were also "legitimate reasons" for these, such as those used by some charities.