The tenth and final season of Smallville, an American television series, premiered on September 24, 2010, and consisted of 22 episodes. It was the tenth and final season to air, and the fifth one to air on The CW television network. The series recounts the early adventures of Kryptonian Clark Kent as he adjusts to life in the fictional town of Smallville, Kansas, during the years before he becomes Superman.

Regular cast members during season ten include Tom Welling, Erica Durance, Justin Hartley, Cassidy Freeman, and Allison Mack. John Schneider, Annette O'Toole, John Glover, Laura Vandervoort, and Callum Blue all returned sporadically throughout the season as did Jonathan Kent, Martha Kent, Lionel Luthor, Kara, and Zod respectively, while Michael Rosenbaum (Lex Luthor) and Aaron Ashmore (Jimmy Olsen) returned for the series finale.

In the final season of the series, season ten continues the romance first developed between Clark Kent and Lois Lane in season nine, as well as the continuation of Clark's trials, and the forging of his superhero identity "Superman". The season premiere was seen by 2.98 million U.S. viewers. The series finale aired on May 13, 2011. By the end of this season, Smallville had become the longest running science fiction television series in North America.

It's amazing to think that Chloe Sullivan and I have been one and the same for over a third of my life, I'm truly humbled by the love and loyalty of all the fans whose enthusiasm has carried me — along with a cast and crew that has become my second family — over the past nine and a half years. Out of respect for the amazingly loyal fans and the place I will always have in my own heart for Chloe, I'm coming back for several episodes next season to tie up Chloe's Smallville legacy properly. It's been a life-changing ride, and I look forward to what lies ahead with the strength of a 'superhero' as my foundation.

In March 2010, The CW renewed Smallville for its tenth and final season, which consists of 22 episodes. Tom Welling, Erica Durance, Cassidy Freeman, Callum Blue, and Justin Hartley were the only regular cast members from the previous season who were contracted for the tenth season, although Blue was not picked up for the second year of his deal. As Allison Mack's contract was reportedly not renewed before the end of season nine, her status was in question, although executive producer Brian Peterson was "very optimistic" that Allison Mack would return.

The studio's official press release was presented two months later and confirmed that Smallville would be remaining at its Friday, 8 p.m. time slot. It also revealed that Smallville would be reteaming with Supernatural, a series that was originally slotted just behind Smallville on Thursday nights for four seasons. The press release did not list Mack in the list of stars. Mack released a statement that month that she would not return as a series regular, but would return for multiple episodes to wind up her storyline, while Peterson stated that, despite her long absence and limited episode count, Mack would remain a series regular. Mack said that her hope was that the character of Chloe will hold on to her integrity as the writers closed out her storyline. For the actress, watching as her character matured over the years—from sacrificing the things she wanted for the sake of her friends, to finally reaching a point where she can strive to satisfy her own needs and wants—has been important for her. Tom Welling, who served as a part-time producer for season nine, was promoted as a full executive producer for season ten. Welling was also set to direct two episodes during the season, and Justin Hartley was contracted to direct another episode.

Souders and Peterson revealed that the theme for season ten is "facing the ghosts of your past and how [the effect of seeing the past] helps you move on in the future"; as such, the return of previous cast members played into this. Souders and Peterson also chose not to erase Lois's memory of Clark's secret, something she discovered in the season nine finale. Instead, Lois helped Clark do what he needs to do to get away and fulfill his destiny without telling him that she knows. The producers explained that there are "some twists and turns" before Lois tells Clark that she knows. Initially helping Clark and Oliver at Watchtower, Tess discovers a secret from her past, and the season explores whether she ends on the side of good or bad. Chloe's ending was also told in a way that was fitting for Chloe. She "sacrifices" herself for Oliver, who has been informed that she was killed. As a result, Oliver spends much of the season looking for Chloe, trying to find who is behind her murder. In addition, Oliver is "literally and figuratively stripped down to his bare essence" early on this season.

Similar to season eight and nine, the tenth season introduced a new main villain, Darkseid, but producers said that it is a different incarnation than his comic book counterpart. They explained that Darkseid's presence is felt throughout the whole season, but that he does not actually appear until near the end, unlike in previous seasons where the main villain was present from the start. Instead, Darkseid's minions—Granny Goodness, DeSaad, Glorious Godfrey, and others to be named—appear throughout the season as the physical presence for Clark to battle. That said, Darkseid makes an appearance in the season premiere, digitally created to start with, but with "more solid forms" making a short appearance by the third episode. The plan is for Darkseid's presence to be established as he takes over the bodies of various characters. The executive producers also wanted to take a look at the history of Smallville's Clark Kent in the 200th episode of the series. According to Peterson, the episode explores the past, the present and the future.