As of July 2026, Supergirl Season 3 aired in 2017 with 23 episodes — streaming now on HBO Max. Full episode guide and where to watch below.

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Supergirl Season 3

2017 23 Episodes Drama · Sci-Fi & Fantasy ⭐ 7/10

Right now you can watch Supergirl Season 3 on and — and it goes further with its ideas than most genre entertainment bothers to. A compact run that never overstays its welcome. 4,413 people have weighed in on TMDB, and the verdict leans heavily positive. Melissa Benoist anchors it with a performance that grounds the bigger ideas in something human. Start it whenever you need something guaranteed to land.

Supergirl Season 3 arrived without much fanfare and built its audience the hard way — through word of mouth. The world-building is meticulous, but it is the characters who carry Supergirl Season 3 through its more ambitious moments. As season three returns with all-new supercharged adventures this fall, Kara and team will come up against a new threat in the form of DC Worldkiller, Reign. Melissa Benoist and Chyler Leigh lead a cast that brings real weight to the material. It was aired in 2017. What separates Supergirl Season 3 from lesser genre entertainment is a willingness to let the concept cost the characters something. There is real craft here, even in the moments that do not fully land.

Supergirl Season 3 is satisfying on multiple levels — something to watch and something to think about after. If you have run out of similar titles to watch, this is a strong next pick. It is a manageable watch, easy to fit into a single week. Watch for Melissa Benoist in particular — the performance elevates the material. Satisfying on multiple levels.

📡 Where to Watch Supergirl Season 3

🇦🇺 Australia

HBO Max Amazon Channel

🇺🇸 United States

Netflix Standard with Ads

🇬🇧 United Kingdom

Amazon Prime Video

Amazon Prime Video with Ads

🎬 Supergirl Season 3 — Episode Guide

Kara deals with the loss of Mon-El by focusing all her energy on being Supergirl and the mysterious new threat against National City. Alex confesses a secret to Maggie about their impending nuptials. A citizen of National City has a mysterious connection to Kara, and Lena makes a bold move.

Psi, a thief with psychic powers, attacks National City. Able to immobilize people by tapping into their worst fears, Psi proves a formidable opponent for Supergirl. Meanwhile, James and Lena are at an impasse, and Samantha starts her new job at L-Corp.

Far From the Tree

Eliza throws Alex and Maggie a wedding shower, which causes Maggie to reach out to her estranged father. Supergirl joins J’onn on a personal mission.

Kara investigates a secretive new group whose leader, Thomas Coville, has a mysterious connection to Supergirl. Meanwhile, Samantha feels like she's letting Ruby down, and J'onn confesses an old secret.

When multiple children get sick from lead poisoning, Morgan Edge points the finger at Lena and blames her creation of the lead bomb she made to save National City from the Daxamites. While Lena knows she never intended any harm, she fears there may have been a flaw in her design, leaving her respons...

Kara and Alex head home to Midvale for a little R&R. While there, Kara recalls a painful memory of a childhood friend's death and how that traumatic experience brought the Danver sisters closer together.

When Winn and the team discover an alien ship has crash landed deep underwater beneath National City, Kara/Supergirl is called in to investigate. Meanwhile, Hank attempts to bond with his father, Myr'nn. Samantha, eager for some understanding of the changes she has been experiencing, looks to her es...

Crisis on Earth-X (I)

Barry and Iris’s wedding brings the gang together, but things go awry when villains from Earth-X attack the ceremony. All of the superheroes band together with help from their super friends like Citizen Cold, The Ray, Felicity Smoak, Iris West and Alex Danvers to take on their most formidable villai...

Supergirl investigates a mysterious symbol popping up all over National City, tracing its origins back to an ancient prophecy and the mark of the World Killer, Reign. Meanwhile, the tension between Lena and Morgan Edge continues to build, causing James to step in and offer up some protection, and po...

Legion of Superheroes

Struggling to heal from her injuries inflicted by Reign, Supergirl remains in a dreamlike state, unable to be reached. Mon-El recruits one of the Legion members, Brainiac-5, to try to bring her back. Meanwhile, Reign continues her rampage on the city so the DEO teams up with the Legion of Superheroe...

As Reign continues to terrorize the city, Supergirl teams up with Saturn Girl, and the two recruit Supergirl’s former enemies, Livewire and Psi, to form a team for a mission to Fort Rozz to recover a prisoner who has information on how to defeat Reign once and for all. Meanwhile, Alex babysits Ruby.

Someone tries to kill Morgan Edge and he barely survives. He accuses Lena of being behind the attempt and vows to destroy her. When Lena fears her hatred for Morgan will take her to the Luthor dark side, Kara steps in to help her friend. Meanwhile, after Sam realizes she’s losing time, she confides ...

The DEO captures a second Worldkiller, Purity. Supergirl and Alex use very different methods of interrogation with Purity in the hopes of finding out how to defeat Reign. However, Purity escapes and attacks the city’s subway tunnels. Meanwhile, J’onn, Winn and Mon-El band together to fix the Legion ...

Schott Through the Heart

When Winn’s father dies, his estranged mother, Mary, reappears trying to reconnect and to explain why she abandoned him all those years ago. Winn is too embittered from his rough childhood to forgive her but when a copycat Toyman attacks, the two must work together to stop him. Mon-El tells Kara som...

In Search of Lost Time

Myr'nn inadvertently causes psychic disturbances at the DEO; Supergirl must work with J'onn to contain the chaos; Mon-El begins training Kara in fighting techniques he's learned in the future.

Supergirl and Imra have different ideas on how to stop the third Worldkiller, Pestilence. However, when both Alex and Winn are seriously injured by Pestilence, Supergirl and Imra team up to stop the destruction.

Still reeling after learning about Lena’s secret, Supergirl asks Guardian for a favor that could alter his relationship with Lena forever. Meanwhile, with all three Worldkillers united, Supergirl and the team brace for an epic battle.

Shelter from the Storm

When Reign starts hunting Ruby, Supergirl and Alex work together to keep her safe. Supergirl and J'onn look to Sam’s mother for advice on how to stop Reign and come away with some shocking news.

When Tanya, a disciple of Coville's, escapes from what's left of his cult, she gives Kara and James a journal that could hold the key to saving Sam. Someone learns Guardian's identity and threatens to expose James if he doesn't do what they ask. James contemplates what it means to be a black vigilan...

Dark Side of the Moon

Supergirl is stunned to discover that a part of Krypton survived. Meanwhile, Alex is attacked while out with Ruby, and Lena considers how far she will go to keep Reign contained.

🎭 Cast of Supergirl Season 3

Melissa Benoist

Melissa Benoist

Kara Danvers / Supergirl / Kara Zor-El

Chyler Leigh

Alex Danvers / Sentinel

David Harewood

J'onn J'onzz / Martian Manhunter

Katie McGrath

Odette Annable

Samantha Arias / Reign

Chris Wood

Jeremy Jordan

Mehcad Brooks

James 'Jimmy' Olsen / Guardian

📋 All Seasons of Supergirl

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