The union-backed group that successfully fought to defeat Ohio's contentious collective bargaining law spent more than $29 million in the fall ballot campaign.
Campaign finance reports filed Friday show We Are Ohio raised about $30 million in its effort and received another $12 million in in-kind contributions.
Final results of last month's election released on Friday show voters rejected the new law 62 percent to 38 percent.
The bill would have restricted the bargaining abilities of more than 350,000 unionized public workers.
The group that defended the law was far outspent. Building a Better Ohio reported spending more than $11 million through its political action committee.
The Republican-backed coalition also trailed the law's opponents in fundraising - bringing in roughly $11 million in donations and about $570,000 in in-kind gifts.