The websites associated with the domain names were allegedly run by organised crime gangs that purported to sell designer items - clothes, jewellery and electronic goods.
Brand names included including Ugg Australia boots, ghd hair straighteners, and jewellery from Tiffany & Co and Links of London.
Shoppers were duped into spending millions of pounds on what seemed to be bargain buys, but received either nothing at all or counterfeit products, the PCeU said in a statement.
"Victims also ran the potential risk of the criminals stealing their identity for misuse elsewhere. The websites are thought to have generated millions of pounds for the gangs which could then be used to fund other illicit activity," the unit said.
PCeU head detective superintendent Charlie McMurdie said, fraudsters exploited the victim's desire to buy designer goods at reduced prices in the run up to Christmas.
"The risk begins when your desire to purchase blinds your judgment or leads you to illegal websites. If it looks too good to be true, it probably is," she said.
The news came as Nominet, the registrar for the .uk internet domain, reported it had registered the eight millionth .uk domain name, lambethsuperhomes.org.uk, in November. A million .uk domain names had been registered since since August 2008, it said.
Nominet is also fighting to retain its independence in the light of proposals in the Digital Economy Bill now going through parliament to give the home secretary the final say in .uk domain name registrations