Many different pants colors will complement a navy blue blazer, including gray, lighter denim and khakis, Business Insider notes. A person can also pair their blazer with pants that are brown or green.
For a professional look appropriate for work, a fancy dinner or that first job interview, try pairing the blazer with khakis, fashion resource Rugged Fellows Guide recommends. Wear a button-down shirt or vest beneath the blazer to really add to the look. Accessorize with a nice watch or a pricier pair of sunglasses to make a great impact.
For a more casual event, such as for a weekend brunch or meeting a romantic partner's parents, pair the blue blazer with lighter denim. Darker denim can make the entire outfit look washed out. Beneath the blazer, try wearing a favorite t-shirt, Business Insider suggests. Finish the look with nice sneakers or loafers and a comfortable belt.
Any shade of gray will pair well with a navy blue blazer, the Rugged Fellows Guide notes. If the gray pants are striped or patterned in any way, this adds some interesting texture to the look. A crisp white shirt beneath the blazer makes the wearer look clean and polished. This look toes the line between casual and professional but is still work-appropriate.