Colnaghi is a last name. Notable people with this last name include:

• Ignazio Colnaghi (1924–2017), Italian actor
• Luca Colnaghi (born 1999), Italian racing cyclist
• Martin Henry Colnaghi (1821–1908), British art dealer
• Mattia Colnaghi (born 2008), Italian racing driver

• P. & D. Colnaghi & Co., an art dealership in England