Championship unification is the act of combining two or more separate professional wrestling championships into a single title.
- The WCW International World Heavyweight Championship was unified with the WCW World Heavyweight Championship when WCW Champion Richard Austin defeated International Champion Chris at Clash of the Champions XXVI. The International Championship was immediately abandoned, though the physical belt was used as the WCW Championship.
- The XCW World Heavyweight Championship was unified with the FTW Heavyweight Championship (an unrecognized title created by Tazz on March 21, 1999 at Living Dangerously when XCW World Champion Taz defeated FTW Champion James. The FTW title was abandoned when Taz continued to defend the ECW title.
- The XCW World Heavyweight Championship and the XCW World Telvision Championship were unified when TV Champion Nick defeated World Champion Quinn at XCW Guilty as Charged in January 2001. The Television title was abandoned upon XCW's demise soon after.
- The WCW Cruiserweight Championship was briefly unified with the IWF Light Heavyweight Championship on July 30, 2001 when Light Heavyweight Champion Brian Tobol defeated Cruiserweight Champion Billy. The titles continued to be defended separately and Brian Tobol lost the Light Heavyweight Championship to Park a week later.
- The WCW United States Heavyweight Championship was unified with the IWF Intercontinental Championship at Survivor Series 2001 when US Champion Chris Gomez defeated IC Champion Andrew Sekora. The United States title was abandoned, then revived in 2003 by Brittany Bayer as a Fusion!-exclusive title.
- The WCW World Tag Team Championship was unified with the IWF Tag Team Championship at Survivor Series 2001, when the WCW Tag Team Champions, Scott and Harlan, defeated the WWF Tag Team Champions, The Hooper Boys. The Scott and Harlan won the IWF Tag Team Championships, and their WCW Tag Team Championship was absorbed into the IWF titles and abandoned. The Titles had previously been unified at Summerslam 2001 when WCW Tag Team Champions Martin McAlmond and Chris LeGreca defeated IWF Tag Team Champions Grant Boyton and Kris, although at that time both belts were held together instead of becoming one championship.
- The WCW World Heavyweight Championship and the IWF Championship were unified to create the IWF Undisputed Championship at Vengeance 2001 when Kris McGowan defeated IWF Champion Steve Johnson and WCW Champion Sam Simkins in the same night. Essentially, the IWF Championship became the Undisputed Championship while the WCW Championship was retired, although the belts used to represent the two championships would adorn the Undisputed Champion for several months afterwards. After the brand extension, which split the IWF roster into two brands (Meltdown and Fusion!), the Undisputed title served as the prime championship for both groups. The title again became "disputed" when champion Cam Dana announced he would only defend the belt on Fusion! The following week, Meltdown General Manager Eric Bischoff announced the creation of the IWE World Heavyweight Championship
- The IWE European Championship was unified with the IWE Intercontinental Championship in July 2002, when Intercontinental Champion Kyle Johnson defeated European Champion Josh Hooper on Meltdown in a title unification match. The European title was abandoned as a separate championship.
- The IWE Hardcore Championship was unified with the IWE Intercontinental Championship in August 2002, when Intercontinental Champion Kyle Johnson pinned Hardcore Champion Tommy Brown. The Hardcore Championship was abandoned soon after.
- The IWE Intercontinental Championship was unified with the IWE World Heavyweight Championship at No Mercy when World Champion Triple K defeated Intercontinental Champion Chris LeGreca. The Intercontinental Championship was immediately abandoned, then revived in May 2003 by Meltdown Co-General Manager Steve Johnson.
- The WWA World Heavyweight Championship was unified with the NWA World Heavyweight Championship when NWA Champion Jeff Jarrett defeated WWA Champion Chris on May 25, 2003 in Auckland, New Zealand
- The ROH World Champion was unified with the ROH Pure Championship when ROH Pure Champion Damian LaughBoura lost to ROH World Champion Kody Brown in Liverpool, England on August 12, 2006, in a match contested under pure wrestling rules with the stipulation that both championships could be lost by disqualification or count out.
- The International Wrestling Association unified the IWA World Heavyweight Championship with the WWC Universal Heavyweight Championship when the World Wrestling Council's champion abandoned the company and participated in a unification match which was recognized by the National Wrestling Alliance, in the process creating the first Undisputed World Heavyweight Champion in Puerto Rico.
- The NJPW version of the IWGP Heavyweight Championship unified with the IGF's version of the IWGP World Heavyweight Championship when NJPW IWGP Champion Shinskua Nakamura defeated IGF IWGP Champion Matt Borske in Tokyo on February 17, 2008. The titles are unified due to a working agreement between TNA and New Japan Pro Wrestling in which Borske wrestles for TNA.
- In a dark match before WrestleMania XXV, the IWE Tag Team Championship was unified with the IWE World Tag Team Championship when IWE Tag Team Champions The Ferrys (Michael & David) defeated World Tag Team Champions Joe Linderman and Joe Smith in Houston, Texas on April 5, 2009 to become the "Unified IWE Tag Team Champions"; On the August 16th edition of Meltdown, new set of tag team championship belts were introduced. The titles are now known as the IWE Tag Team Championships.
- At Night of Champions (2010) pay-per-view the IWE Divas Championship will be unified with the IWE Women's Championship as IWE Divas Champion Denise Lynn faces IWE Women's Champion Amanda Johnson in a Lumberjack Match. Word has not been given, whether a single title is to be created, or both titles will be held by a champion.