Sainsbury's head of public affairs Erica Zimmer confirmed FH would manage a wide-ranging commercial lobbying brief, following a pitch revealed in PRWeek last month (PRWeek, 11 February).
The agency replaces Lexington Communications, the supermarket's UK public affairs adviser of four years. Sainsbury's has also replaced seven-year incumbent agency Fleishman-Hillard Public Affairs, which has handled its PA in Brussels, with local PA specialist Cabinet Stewart (CS).
CS pitched jointly with FH and is to take on European Union lobbying work from next month.
Sainsbury's plans to increase the number of its in-store pharmacies as the sector is deregulated.
The group has 121 pharmacies across its 735 stores and hopes to add 50 more outlets.
Deregulation will mean pharmacy licences could be fast-tracked and given to stores that stay open for more than 100 hours a week.
Last week, the Financial Times reported that Lord Sainsbury, Labour's science and innovation minister, had given £2m to the Government's election war chest.
The billionaire holds the biggest share in Sainsbury's through a blind trust.