The Sentry Group started off in 1930 as a small shop set up by John Brush and William Punnet. In 1943, John Brush purchased his partners' interest, and became the sole owner of the company. In 1955, it was named John Brush & Co. by his son, John Brush Jr., who took over the company then. In 1968, the company moved into a new plant at Rochester, New York. In 1987, it took the name 'Sentry Group', so as to identify itself better with the 'Sentry Safes' that it manufactured.

Currently, the Sentry Group manufactures file cabinets, fire-proof safes, chests, containers for secure storage, gun-safes and even enclosures for hard-drives of computers that will render them resistant to crashing, fire, water and theft in collaboration with Maxtor , a hard-disk manufacturing company. The company has a manufacturing plant in Shanghai, China as well. Sales offices of the Sentry Group are located in Canada, Japan and the UK as well.

The company in collaboration with national independent testing firm, ETL Semko, is known for the rigorous tests it puts each manufactured safe through in order to ensure complete safety and conformation to standards and norms. Detailed fire-resistance and water-resistance tests that last more than an hour each prove that SentrySafes are really as effective as they are said to be. The safes are also tested in rock-pits, where they are dropped from a height of 30 feet. The safes are designed to withstand physical shocks, even after being exposed to extremely high temperatures that could have arisen during fire accidents. Waterproof safes from the Sentry Group keep their contents dry even after being completely submerged in 6 inches of water for more than an hour.

The Sentry Group has won several awards for its unique product design and retail service. It has also won the "Vendor of the Year" award from Lowe's, Walmart and OfficeMax in 1999, 2001 and 2002 respectively.