Maualuga, a second-round draft pick from USC, is expected to compete for a starting job at outside linebacker when the Bengals open training camp on Friday in Georgetown, Ky.
Later in the day, the Bengals signed third-round pick Michael Johnson, a defensive end from Georgia Tech.
Only Smith, the No. 6 overall pick, remains unsigned.
James Walker covers the AFC North for ESPN.com. Information from The Associated Press was used in this report.