The company, which has 1,000 employees across the four sites and an annual turnover of £101m, supplies the top six UK supermarkets.
Fletchers was sold by Northern Foods to Vision Capital in 2007, but was allowed to continue using its former owner's customised verson of MySAP 2004 until it found a replacement.
"We wanted to move as quickly as possible to a system that would enable us to continue working, but that was a standard product that would be easy to maintain and upgrade by ordinary business users," said Chris Hassell, programme manager at Fletchers Bakeries.
Lawson's business intelligence (BI) software will allow Fletchers to make use of business planning and analytical functionality within a single, integrated system for the first time.
"This will be a huge business benefit in enabling us to supply the right quality and quantity of products to our customers, which is one of the biggest challenges of being a supplier to the big six UK retailers," he said.
The company will use the BI component of the Lawson software to improve its production efficiency through detailed analysis of its consumption of human resources and raw materials.
Christian Hestermann, an ERP research director at Gartner, said, "Choosing industry-specific software saves costs at implementation by eliminating the need for third party systems integrators, and also in the long run by enabling an automatic upgrade process."
The boundaries between business applications and the reporting and analytical applications were being broken down and brought closer together by software suppliers in response to customer demand, he said.
Fletchers has begun a phased roll-out of the Lawson software across its four production sites, starting with its Manchester site due to go live in May, followed by its London and Barnsley sites in June, and finishing with its Sheffield site, due to go live in July.
After short listing three products, including SAP, Fletchers chose Lawson's M3 ERP for the food and beverage industry because of a lower total cost of ownership and 50% faster implementation time.