Many Kosher products are available in local supermarkets (HEB, Randalls, Kroger, Trader Joes, Whole Foods).

HEB on Market Street has a small Kosher section. They typically carry, grape-juice, bamba, chocolate, yartzeit candles etc. For Passover, they have a decent selection of Matzah and dry-goods.

Locally, the largest selection and best-quality Kosher chicken, beef and lamb, are available at Chabad of The Woodlands (items are frozen). Click here to see what's available.

Trader Joes on the corner of Woodlands Pkwy and Gosling carries a limited selection of fresh Kosher meat and chicken under the Teva and Empire brands. Whole and cut-up chicken, brisket, ground beef, stew meat and rib-eye.

Total Wine has quite a selection of Kosher wine. Specs carries some too.

There is also a Facebook page that updates local Kosher options. 

However, the widest range of Kosher products will be found in the Houston supermarkets