More than 40 UK high street retailers opened their doors at midnight, while others saw queues of buyers forming in the early hours of the morning.
GTA IV is also tipped to break the opening week sales figures of Microsoft's Halo 3, by selling an expected nine million copies, pulling in up to £200m.
Stuart Rowe, Chief Operating Officer at e-retailer Play.com said: "Grand Theft Auto IV is going to break all previous records when it comes to gaming. We're experiencing trading levels similar to those seen in the run up to Christmas, taking over 80 orders per minute at peak times."
However, according to online spam-blocking software service ClearMyMail.com, web hackers have jumped on the game's success by targeting those who failed to get hold of a copy of the game .
GTA fans worldwide are being sent spam emails that offer free entry into a competition to win a PS3 and GTA IV. However, the emails actually contain spyware and Trojans intended to steal personal financial information and attack victim's computers.
"We are seeing unprecedented levels of spam in relation to the game; with more than half of the spam our service is blocking relating to Grand Theft Auto, most of which contain viruses and spyware," commented Dan Field, Managing Director of ClearMyMail.
"My advice to anybody who receives these emails is to refrain from opening it, and to wait until they can legitimately purchase the game," he added.