Workers' Freedom to Negotiate Act of 2018 This bill amends the National Labor Relations Act (NRLA) and related labor laws to extend protections to union workers. Specifically, it: revises the definition of "employee" and "supervisor" to prevent employers from removing employees from the protections of the labor laws, prohibits employers from interfering with certain rights granted to employees under the NLRA, expands unfair labor practices to include prohibitions against replacement of worker who strike or discrimination against them, imposes new penalties against employers who violate labor law requirements, allows workers to bring civil actions against employers for labor law violations and unfair labor practices, requires certain disclosures with respect to worker wages, and requires contractors seeking federal contracts over $500,000 to disclose labor law violations when applying for such contracts.