The chamber’s political action committee endorsed the Democrat after both he and Republican Bill Maloney addressed the business group’s annual summit last week.
The business group had endorsed Tomblin in the May Democratic primary. It also supported both Maloney and Betty Ireland in the Republican primary.
Chamber officials said Wednesday’s endorsement results from Tomblin’s experience, leadership, and ability to work with the Legislature. Tomblin is acting as governor while Senate president.
The Charleston Regional Chamber of Commerce endorsed Tomblin last week. Tomblin also picked up support from West Virginia’s largest labor organization, the state AFL-CIO. The special election is Oct. 4. Six third-party, independent and write-in candidates are also running.