Tim Warrillow, who co-founded the group with Charles Rolls in 2004, said he was responding to demand from big investors for shares in the firm.
The move reduces his stake to 5.4% and comes after Mr Rolls banked £73m through selling shares in May.
Shares in the firm, best known for its tonic water, have soared more than 1,000% since 2014.
This year alone shares in the group, which also sells mixers such as ginger beer and Sicilian lemonade, have risen by more than 50%.
Fever-Tree's international sales have expanded rapidly, and more than 50% of its revenues now come from outside the UK.
The US, Spain and Belgium are key overseas markets.