Members approved the Postal Services Bill by a majority of 81 earlier today (13 January).
The Bill allows for up to 90% of the postal operator to be sold to a private company with the rest handed to Royal Mail employees.
The Post Office will be spun off and remain in public hands.
Business secretary Vince Cable says that privatisation is necessary to attract the investment needed to modernise the business.
He adds: “Since taking office the government realised it had to move swiftly to tackle the challenges facing Royal Mail and the Post Office to ensure the future of the important services they both provide.
“We’re absolutely determined to secure the future of these two proud institutions.”
Opposition MPs and union leaders argue that the bill fails to protect the Royal Mail’s commercial relationship with the Post Office, which could lead to higher prices for consumers.
Royal Mail’s rivals say that a private or part-private competitor would lead to increased competition in the postal services sector and could lead to cheaper direct mail services and increased options for marketers.