The site was hit by an SQL attack which installed malware, including a Trojan.
The attack was made on 14 July and visitors to the nigella.com domain may have picked up an infection if their browsers were not fully patched.
Eldar Tuvey, chief executive of ScanSafe, which detected the attack, said: " SQL injection attacks have become the most common form of website compromise, outpacing all other types by 212 per cent.
"High profile websites such as Nigella Lawson's must realise that they are becoming an appealing target for cyber-criminals.
"The compromise of legitimate and trusted websites has contributed to a 278 per cent increase in web-based malware for the first half of the year."
Visitors to the site are advised to update their antivirus signature files and perform a full scan as soon as possible.
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iTnews Executive Retreat - Security Leaders Edition
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