Around 5,000 businesses across the country have been hit by the fallout of the attack, according to research from the Cyber Monitoring Centre (CMC).
Experts from the non-profit organisation have analysed the impact of the cyber attack across the economy and wider supply chain.
JLR stopped production across its UK factories for five weeks from September 1 after being targeted by hackers.
The incident also led to warnings from suppliers that they could collapse without trading rapidly resuming or financial support.
Ciaran Martin, chair of the CMC’s technical committee, said: “With a cost of nearly £2 billion, this incident looks to have been by some distance, the single most financially damaging cyber event ever to hit the UK.
“That should make us all pause and think, and then – as the National Cyber Security Centre said so forcefully last week – it’s time to act.
“Every organisation needs to identify the networks that matter to them, and how to protect them better, and then plan for how they’d cope if the network gets disrupted.”
The CMC predicted that more than half of the cost will be shouldered by JLR itself due to lost earnings and money spent on its recovery.
The organisation added that it does not expect a full recovery from the incident until January 2026.
It said it categorised the hack as a category 3 incident, based on its scale where a category 5 is the most severe.
Recent cyber attacks on UK retailers, such as M&S and the Co-op, were deemed a category 2 incident.
