Knaack is the CEO of Knaack KG, a real estate company. He was previously a partner and general manager of Knaack Enterprises, a 125-year-old family business.He is a founding member of the Civic Foundation of the City of Ratzeburg and served as president of the Golf-Club Gut Grambek. Knaack is also the founder and chair of the Karl Adam Foundation.

A Rotary member since 1992, Knaack has served Rotary as treasurer, director, moderator, member and chair of several committees, representative for the Council on Legislation, zone coordinator, training leader, and district governor.

He is an endowment/major gifts adviser and was co-chair of the Host Organization Committee for the 2019 Rotary International Convention in Hamburg. Knaack and his wife, Susanne, are Major Donors to The Rotary Foundation and members of the Bequest Society.