More than one in three people have bought goods using the internet from their office computer while at work, according to research.
Even more have booked holidays, made banking transactions, and sent e-mails to friends and relatives, according to a survey of 500 employees.
Britain's long working hours culture could be one reason why people increasingly organise their personal lives while at work, broadband provider Pipex said.
Its survey showed two-thirds of people planned their holidays in the office. One in 10 even looked for another job.
Dominic Crolla, managing director of Pipex, said: "We know spending online is on the up, so it is little wonder British workers are swapping window-shopping for workstation-shopping."