It has acquired one of Scotland's oldest and biggest poultry businesses Forfar-based Joseph Mitchell (Letham) which was founded in 1904 and employs 153 staff in Angus.
Terms were not disclosed, but it is believed the transaction resulted in a multi-million windfall for the three Mitchell brothers who owned it.
Mike Mitchell said the sale followed an approach from the West Bromwich-based 2 Sisters, which made the offer to good to dismiss. "We think we have done a deal that protects the staff, customers and sales of the Group. 2 Sisters are a good strong food group."
The three brothers, who will remain in management roles at Scot Lad, were the fourth generation to run Joseph Mitchell.
This week's sale came 10 years after the brothers brought control of Jospeh Mitchell back into the family's hands through a £5.5m management buy-out from Saltire which had bought the company in 1987.
The 2 Sister Group has also expanded its added value poultry division with the purchase of Challenger Foods, a processed meat supplier based in Sunderland, and Tulip's Morecambe facility. These two businesses already cook and roast poultry for the major retailer and foodservice markets.
Chief executive of 2 Sister Group Ranjit Singh highlighted that the expanded division would have a combined turnover of £100m. "These acquisitions fit with our strategy to broaden the poultry offering and geographic reach of our Group. In addition it will allow us to provide consumers with more locally sourced products, thus helping us to reduce our carbon footprint," he said.