Research from Zurich UK found 4,562 cases of employee theft were reported to 39 police forces across England and Wales.
Each theft cost businesses up to £35,728.
The Metropolitan Police recorded the most cases with 794 incidents in London.
Gloucestershire saw the biggest decline, dropping 46% from 93 thefts in 2023 to 50 last year.
Zurich’s claims included a £249,229 loss at a high-end jeweller, £63,439 at a furniture company, and £50,000 at a medical centre.
Robert Higgs, senior speciality lines claims expert at Zurich, said: “Employee theft takes on many forms, from petty theft of stationary to fraud and embezzlement, which can cost hundreds of thousands of pounds and be devastating to businesses.
“The decline in such thefts could be attributed to various factors including a rise in companies investing in advanced AI fraud detection systems, better security measures and cashless payment models.
“By helping businesses address weak spots, such as enhancing digital security, it’s possible to prevent theft and reduce claims.”
Higgs added: “Zurich prides itself on working with customers to help in any way possible with loss prevention.
“Preventing any claim is beneficial to all parties and helps to keep premiums as low as possible.”
Will Anderson, head of UK specialty lines claims at Zurich Insurance Company Ltd, said: “It’s positive to see a decline in the number of reported thefts in the workplace, given the ongoing burden of a high cost of living.
“Despite this decline in volume and enhancement in technology, no business is immune from this type of theft which can occur at all levels of an organisation.
“Crime Insurance provides vital protection that can help mitigate the impact of these financial losses and help businesses resume normal operations in a swift fashion.”
The research found the most common types of workplace theft included cash, goods or stock, data, intellectual property, and embezzlement.
Zurich advised firms to carry out background checks, set clear procedures, use dual approval for payments, keep receipts, carry out random audits, build a positive work environment, provide whistleblowing channels, and invest in strong cyber security to help reduce risk.