The 2018 Fastlane was the fourth Fastlane professional wrestling pay-per-view (PPV) and livestreaming event produced by WWE. It was held exclusively for wrestlers from the promotion's SmackDown brand division. The event took place on March 11, 2018, at the Nationwide Arena in Columbus, Ohio. The 2018 event was the final SmackDown-exclusive pay-per-view and subsequently the final brand-exclusive pay-per-view under the second brand split as following WrestleMania 34 in April, WWE discontinued brand-exclusive PPVs.

Seven matches were contested at the event, including one on the Kickoff pre-show. In the main event, AJ Styles retained the WWE Championship in a six-pack challenge against Kevin Owens, Sami Zayn, Baron Corbin, Dolph Ziggler, and John Cena. In other prominent matches, Randy Orton defeated Bobby Roode to win his first United States Championship, becoming the eighteenth Grand Slam Champion in the process, and Charlotte Flair retained the SmackDown Women's Championship against Ruby Riott, after which, women's Royal Rumble winner Asuka from the Raw brand made her SmackDown debut to challenge Flair for the title at WrestleMania 34.

Fastlane was a professional wrestling event first produced by WWE in 2015. The name of the event was a reference to its position on the "Road to WrestleMania", being held in the two-month period between the Royal Rumble and WWE's flagship event; the first two Fastlane events were held in February before moving to March. While the 2017 event was a Raw-exclusive pay-per-view (PPV), the 2018 event exclusively featured wrestlers from the SmackDown brand division. Announced on December 4, 2017, the fourth Fastlane was held on March 11 at the Nationwide Arena in Columbus, Ohio. The event aired on pay-per-view worldwide and was livestreamed on the WWE Network. Tickets went on sale December 8 through Ticketmaster.

The event comprised seven matches, including one on the Kickoff pre-show, that resulted from scripted storylines, where wrestlers portrayed heroes, villains, or less distinguishable characters in scripted events that built tension and culminated in a wrestling match or series of matches. Results were predetermined by WWE's writers on the SmackDown brand, while storylines were produced on WWE's weekly television show, SmackDown Live.

At the Royal Rumble, AJ Styles defeated Kevin Owens and Sami Zayn in a handicap match to retain the WWE Championship, although Owens, who was pinned, was not the legal man. On the following episode of SmackDown, Owens and Zayn interrupted 2018 Men's Royal Rumble winner Shinsuke Nakamura and said that they should be the co-WWE Champions, but the referee failed at his job. Styles and Nakamura then teamed up and defeated Owens and Zayn. During the match, there were tensions between Owens and Zayn as a result of General Manager Daniel Bryan scheduling them to face each other the following week to determine the number one contender for the WWE Championship at Fastlane. Their match ended in a double disqualification, however, as Styles was provoked by Zayn and attacked both men, leading to Bryan scheduling a triple threat match between the three for the title. Commissioner Shane McMahon then announced on Twitter that the winner of a match between Dolph Ziggler and Baron Corbin the following week would be added to the championship match to make it a fatal four-way. Before that match started, Owens and Zayn attacked Corbin in the backstage area and later went after Ziggler to prevent either from being added. In response, Shane scheduled Owens to face Corbin and Zayn to face Ziggler, with both Corbin and Ziggler being added if they won their respective matches, while also threatening that if Owens or Zayn interfered in the other's match, that person would be removed from the title match. Corbin and Ziggler won their respective matches, thus making it a fatal five-way for the WWE Championship at Fastlane. On the February 27 episode, John Cena, a non-exclusive wrestler who could appear on Raw and SmackDown, who was unsuccessful in becoming the number one contender for Raw's Universal Championship at Elimination Chamber two nights prior, made his return to SmackDown, determined to earn a match at WrestleMania 34. Bryan gave him the opportunity to be added to the WWE Championship match at Fastlane if he could defeat Styles in a non-title match. Cena defeated Styles, turning the championship match into a six-pack challenge. A brawl then ensued between all six competitors. To keep himself from being interrupted, Cena appeared on the March 5 episode of Raw and said that he would break his and Ric Flair's tied record and become a 17-time world champion, and said that Styles should use his rematch clause to make the WWE Championship match at WrestleMania a triple threat match with Nakamura. On the final SmackDown before the pay-per-view, Owens and Zayn caused a double disqualification in a match between Styles and Ziggler; a five-way match with the addition of Corbin was scheduled, which saw Zayn score the win by turning on and pinning Owens.

Immediately following the Royal Rumble, General Manager Daniel Bryan announced that there would be a first-ever "SmackDown Top Ten List" as voted on by the SmackDown roster. Bryan said the list would show who the wrestlers thought should get a title opportunity, but a wrestler could not vote for themselves. The Top Ten List was revealed on the February 6 episode of SmackDown. The following week, United States Champion Bobby Roode, Jinder Mahal with Sunil Singh, and Randy Orton all exchanged words as Mahal made fun of their spots on the list despite Mahal not ranking at all; Orton and Roode were 9th and 5th, respectively. The segment ended after Orton attacked Sunil with an RKO, and Mahal performed the Khallas on Roode and Orton. The next episode, Mahal again called out Roode and Orton, and a brawl broke out in which Roode attacked Orton with a Glorious DDT, but suffered a Khallas from Mahal, who stood tall once again. Despite this, Commissioner Shane McMahon scheduled Roode to face Orton for the United States Championship at Fastlane. The following week in a backstage interview, Roode said that in order to be the greatest United States Champion of all time, he would have to beat the best, and said that Orton was one of the best of all time. Orton interrupted and said the U.S. title was the one title he had never held during his WWE career and would be taking it from Roode at Fastlane. On the final SmackDown before Fastlane, Mahal defeated Orton due to an interference by Roode.

Throughout 2017, The Usos (Jey Uso and Jimmy Uso) and The New Day (Big E, Kofi Kingston, and Xavier Woods) wrestled at numerous events over the SmackDown Tag Team Championship, with the original feud ending at Hell in a Cell with The Usos victorious. The Usos' next feud were with Chad Gable and Shelton Benjamin, who were unsuccessful in gaining the titles at the Royal Rumble. On the February 20 episode of SmackDown, Gable and Benjamin had another opportunity to become the number one contenders against The Usos for the SmackDown Tag Team Championship at Fastlane, but were defeated by The New Day's Big E and Woods, thus reigniting an old feud. The following week, The New Day said that they wanted to be the SmackDown Tag Team Champions going into WrestleMania 34. The Usos interrupted and said that they had been with the WWE for a number of years, but had never had a spot on the main card at WrestleMania and said that would not be the case at WrestleMania 34. As the two teams had a confrontation, they were interrupted by The Bludgeon Brothers (Harper and Rowan) and retreated.

At the Royal Rumble, Asuka of the Raw brand won the inaugural women's Royal Rumble match for the right to challenge for either the Raw Women's Championship or SmackDown Women's Championship at WrestleMania 34. The following night on Raw, Raw Commissioner Stephanie McMahon convinced Asuka to wait until after Raw's Elimination Chamber pay-per-view to make her decision. On SmackDown, this left SmackDown Women's Champion Charlotte Flair to wonder who her WrestleMania opponent would be. The Riott Squad (Ruby Riott, Sarah Logan, and Liv Morgan) interrupted and said Flair would not make it to WrestleMania before attacking her. Over the next couple of weeks, Flair defeated Morgan and Logan in non-title matches. On the February 20 episode, Flair teamed with Becky Lynch and Naomi in a six-woman tag team match against The Riott Squad where Riott pinned Lynch. Later that episode, Flair offered to put her title on the line at Fastlane against Riott, who accepted.