Google Inc., undaunted by a short-lived attempt to market and sell smartphones on its own, is now trying the approach with tablet computers in a quest to capture market share from Apple Inc.'s iPad.

The Internet search company will sell co-branded tablets directly to consumers through an online store like rivals Apple and Amazon.com Inc., according to people familiar with the matter. The move is an effort to turn around sluggish sales of tablet computers powered by Google's Android software.

Google...