A black corduroy blazer is one of the most versatile pieces of clothing a stylish man can own. You don't have to mortgage the farm to get a decent one, either. Black corduroy blazers are a step below the traditional navy blue blazers on the formality scale; they are comfortable yet elegant, casual yet refined and go with a variety of colours and patterns. But as with all things fashion, some things go better with black corduroy blazers than others.
The Jeans Have It
The ongoing trend of wearing jeans with suit jackets is tailor-made for black corduroy blazers. Something about the blue-and-black combo exudes style and hipness. And whereas shiny suit jackets sometimes contrast too much with the rough denim fabric, corduroy is the ideal complement. Best bests for your black corduroy blazer range from "dirty denim" jeans from a mass retailer, to pricier designer brands.
If jeans are a little too casual, try a black corduroy blazer with matching black corduroy slacks---or charcoal/grey trousers. Tweeds, twills and flannels will all work. In the summer, try khaki trousers with a plain front.
The Rest of the Outfit
Just about any shirt goes with a black corduroy blazer, including solids. A blue shirt will look great if you have blue eyes. Textures, and moderate strips will look good, as long as they're not too big and bold. For the ultra-casual look, T-shirts with jeans are OK, although the T-shirt-and-blazer look is starting to wear thin. Slip-on shoes are almost a requirement if you're going the black-blazer-and-jeans route. Try a hip brand like Doc Martens or Skechers. Stay away from athletic shoes---that's taking the whole casual thing a tad too far.