The firm is expected to fetch up to £500m if the 71-year-old sells up. Media enquiries are being handled by a Brunswick team that includes partner and former Sun editor David Yelland.
Foster + Partners head of comms Katy Harris is working with Brunswick to manage media expectation as Foster enters consultations with City bankers.
If the sale is confirmed, likely suitors are expected to be private-equity companies. Brunswick will have to manage the surge in media interest around the firm.
Both Foster + Partners and Brunswick declined to comment.
Foster + Partners employs some 600 architects and designers, and has been involved in high-profile projects from the HSBC headquarters in Hong Kong to the Millau Viaduct in France – the world’s tallest traffic bridge.