They are joined by Rick Gonzalez as Rene Ramirez and Juliana Harkavy as Dinah Drake, who were promoted to series regulars from their recurring status in the previous season.

The series follows billionaire playboy Oliver Queen (Stephen Amell), who claimed to have spent five years shipwrecked on Lian Yu, a mysterious island in the North China Sea, before returning home to Starling City (later renamed "Star City") to fight crime and corruption as a secret vigilante whose weapon of choice is a bow and arrow.

In the sixth season after an explosive battle on Lian Yu, Oliver must balance being a vigilante, the mayor, and a father to his son William.

At the same time, new enemies emerge, initially led by terrorist hacker Cayden James (Michael Emerson), who allies himself with various criminals including drug dealer Ricardo Diaz (Kirk Acevedo), metahuman vigilante Vincent Sobel (portrayed by Johann Urb, voiced by an uncredited Mick Wingert when masked), Russian mobster Anatoly Knyazev (David Nykl), and metahuman Black Siren.

As James loses control of his cabal and is arrested, Ricardo Diaz comes to the fore and kills him, revealing that he manipulated James into believing Oliver killed his son and announcing to Green Arrow his scheme to take over Star City's criminal underworld and control the city's political infrastructure, all while Oliver must contend with his former teammates forming a rival team.

As Diaz takes control of the city, Oliver is forced to recruit the aid of the FBI, in exchange for him publicly announcing his identity and going to federal prison.

The series was renewed for its sixth season on January 8, 2017, and filming began in Vancouver, British Columbia on July 6, 2017, and ended in late April 2018.

[1] This season includes the fourth annual Arrowverse crossover with TV series The Flash, Legends of Tomorrow and Supergirl, and with elements from Freedom Fighters: The Ray.

Prometheus's partners, Dark Arrow (Oliver's doppelgänger), Overgirl (Kara Danvers' doppelgänger), and Eobard Thawne steal a sublight generator, the Prism, from research company Dayton Optical Systems; Oliver, Barry Allen, Kara, and the others believe that Dark Arrow seeks to build a neutron bomb with it to aid in his conquest of Earth-1.

[60] Guggenheim said the fates of the characters would be revealed in the sixth season, but cautioned, "I know everyone is trying to determine who survives, who dies, what is the result of the cliffhanger based upon people's contractual status, and I would say that's not necessarily a good idea".

[79] The episode "Thanksgiving" re-uses archive footage of Billy Joel from his concert of August 4, 2015, at the Nassau Coliseum in Long Island, performing the song "No Man's Land".

[81] In May 2017, The CW president Mark Pedowitz officially announced plans for a four-show Arrowverse crossover event, crossing over episodes of the television series Supergirl, The Flash, Legends of Tomorrow, and Arrow.

[25] The season was released on DVD and Blu-ray on August 14, 2018, with special features including the fourth annual Arrowverse crossover event titled "Crisis on Earth-X".