In the episode Ke Kinohi, Fat was seen playing golf with the Honolulu Yakuza's crime boss, Hiro Noshimuri when Steve and Detective Sergeant Danny Williams confronted Hiro and Hiro's brother, Koji, about stealing evidence concerning the car bomb murder of Steve's mother and the kidnapping of Steve's sister, Mary McGarrett.
After the arrest of Hiro Noshimuri for arranging the theft, it is implied that Wo Fat was of some importance as he was seen being chauffeured around in a golf cart by a bodyguard.
It was not clear at this point what his role is in the local Yakuza organization until in the episode Ne Me'e Laua Na Paio where Agent Jenna Kaye shows Steve a picture of Wo Fat speaking to Victor Hesse in prison.
Jenna told Steve that Hesse and Hiro both worked for Wo Fat, and that while she was in the CIA she was working on Wo Fat's case. She found that Wo Fat was in Macao and had a CIA send a grab team to capture him, but it turned out to be a trap. The whole team was killed, including Jenna's fiancé, Joshua Hirsch although his fate was not disclosed until later on in the series.
At the end of the episode, Wo Fat confronted Steve in a restaurant where Steve was due to meet Jenna. Wo Fat wanted to know what Steve knew about him so far and also warned Steve not to dig to deeply into the McGarrett family history because Steve might not like what he finds with the confrontation presumably leaving Steve deeply shaken.
In the Season 1 episode finale Oia'i'o, Wo Fat arranges a car bomb that kills Laura Hills, Governor Pat Jameson's assistant, leaving Jameson devastated and Steve hellbent on searching for answers. Steve eventually and personally confronted Jameson by breaking into her mansion where Jameson told him that she had ordered Hill's death after she learned she was sending Steve packages with evidence from John McGarrett's investigation.
During the confrontation, Wo Fat snuck up on Steve and tasered him, using Steve's gun to kill Jameson before fleeing the scene, making it look like Steve killed Jameson. As a result of this Steve was arrested and imprisoned for Jameson's death while Hawaii Five-0 was broken up and their Headquarters shut down.
A week after the Governor's death and Steve's arrest in the episode Ha'i'ole, Chin noticed Wo Fat at Governor Jameson's funeral. After the funeral, Chin approached Wo Fat. His two bodyguards, Pao Dan and Wei Ling, tried to stop Chin but were defeated after a short scuffle.
Chin told Wo Fat that he knew Fat had killed Jameson and that the truth would be discovered, but Wo Fat ignored the warning and congratulated Chin on rejoining HPD before leaving.
After Steve was stabbed by Hesse, Danny and Chin learnt that Hesse was ordered to kill Steve by Wo Fat but purposely didn't so that Steve could escape and get Wo Fat. Hesse knew that after he killed Steve that Wo Fat was going to go for him to "tie up loose ends" before Wo Fat disappeared.
Steve eventually escaped and after he was cleared, he, Danny and Chin attempted to arrest Wo Fat. Through information in Wei Ling's wallet, which Chin Ho pickpocketed during the fight at the funeral, they were able to find out that Wo Fat was arranging an arm's deal involving ingredients for a dirty bomb at a boat harbor.
Kono was observing them but was captured by Wo Fat. He interrogated her to see what she was doing here and finally had Pao Dan take Kono away presumably to be either held or executed.
Kono managed to escape and tipped off 5-0 on the arms deal. Steve, Danny, and Chin raided the boat but didn't find Wo Fat, while Joe and Kono engaged the buyer in a chase before killing the mysterious buyer, finding the bomb materials as well.
Near the end of the episode, Steve learnt of a video recording showing his father meeting both Wo Fat and Governor Jameson but the video had no audio whatsoever. Steve was left harboring doubts, believing his that father might be dirty, remembering that Wo Fat had said not to dig too deeply into his family's past.
Wo Fat was later shown leaving Halawa Correctional Facility after killing Hesse, in a car driven by Jenna Kay.
In Ka Hakaka Maika'i, Joe White brought in NCIS Special Agent Kensi Blye, a lip reader, to try and figure out the purpose of the meeting. The only important thing she could find was the name, "Shelburne". Joe and Steve couldn't figure out the meaning of the word so Joe arranged with Steve to meet Hideki Makoto, a former Imperial Japanese fighter pilot who helped bomb Pearl Harbor and who later became John's friend.
Makoto hired John to investigate corruption in the Police Department and in politics after becoming fed up by both. As John investigated further he found that the Governor was actually in league with the Yakuza and Wo Fat. John couldn't act upon his findings due to threats to his family, including his wife's death.
Wo Fat later confronted Joe White in his apartment to find out what Joe knew. Joe retorted by asking what "Shelburne" was. Wo Fat was left troubled, admitting to Joe that he was surprised by how much Joe and Steve know. Wo Fat then attempted to kill Joe with a gun he was carrying but Joe disarmed him.
The two men then engaged in a brutal fight in which Wo Fat used his greater skill in martial arts to finally get the upper hand on the well-trained Joe. Wo Fat proceeded to strangle him but Joe ultimately freed himself and went for Wo Fat's gun, only to find that Wo Fat had fled.
In Kil'ilua, Wo Fat used a local reporter, Bethany Morris, as a means of giving Jenna Kaye hope that her fiance, Joshua was still alive. The reporter was murdered afterwards and it was revealed that Jenna was working for Wo Fat because he had threatened the life of her fiancé. Jenna lured Steve to North Korea where Wo Fat and his men emerged, capturing Steve.
Jenna was eventually led to where her fiancé was but discovered that he was dead, and had been all along. Wo Fat had been using her hope that Josh had survived to keep Jenna working for him in order to get to Steve. Devastated, Jenna contacted Danny and told him of what was going on while Kono traced the call, prompting the Hawaii Five-0 team to launch an unofficial rescue operation to save Steve.
Back in Korea, Jenna took some medical pins from Josh's knee and she slipped them to Steve while also apologizing for what had happened. After one of Wo Fat's men discovered the satellite phone and showed it to Wo Fat, Fat shot Jenna in the chest in front of Steve.
Steve later used the pins to free himself and sought to escape but was recaptured. In the process of a transfer, Wo Fat's convoy was attacked by Lori Weston's RPG gun while Danny, Kono, Chin Ho, Joe, and a few SEAL operatives from SEAL team 9, who owed Steve for rescuing one of their own, attacked Wo Fat's convoy, saving Steve although Wo Fat escaped in the processed.
A few months later, with his desire to find Joe White and get answers into "Shelburne" growing stronger, Steve eventually albeit temporarily left the team some time prior to Ha'alele and the two crossover episodes with NCIS: Los Angeles, Pa Make Loa and Touch of Death which also resulted in Danny becoming the temporary team leader.
Wo Fat returned in Ua Hopu, when Steve arrests him in Japan and has him extradited back to Hawaii. Their plane, a CIA black flight flying unregistered and under the radar over the Hawaiian jungle, is shot down by the Yakuza, with only Steve and Wo Fat surviving the crash. They are forced to work together to defeat a clean-up team sent to kill them, culminating in them stealing a helicopter. They are intercepted on landing by the Yakuza, led by Adam Noshimuri, who blames Steve and Wo Fat for the death of Hiro Noshimuri, his father and the Yakuza's original leader. The arrival of the rest of Five-0, and Kono's personal plea to Adam, sees the Yakuza back down from killing Wo Fat, who is sent to jail.
In La O Na Makuahine, Wo Fat was on the verge of being transferred but the prison truck he was in was knocked off the road, resulting in Fat being freed.
It was later revealed that Frank Delano was the man responsible for breaking Wo Fat out of prison with the team striking a deal. Delano and his men would be able to get drugs off the island in exchange for giving Wo Fat the location of Shelburne, who was also revealed to be Doris McGarrett, Steve's supposedly dead mother.
Wo Fat eventually confronted Doris in Steve's home, resulting in a stand off, holding each other at gunpoint. However, Doris fired three shots into the ground, giving Wo Fat time to escape although it's not known the reason why she allowed this.
In Hana I Wa 'Ia, Wo Fat kidnapped a congressman and was about to kill him until Steve and Danny's arrival in a helicopter. Danny exchanged fire with Wo Fat during the rescue, but Wo Fat managed to escape once again.
In Imi Loko Ka 'Uhane, Wo Fat returned, disguised as a police officer, and was interviewed by chat show host Savannah for her show about the Five-0 task force. Steve noticed Wo Fat during that interview and gave chase, firing several shots, but Wo Fat evaded capture. Wo Fat was later severely injured during a gunfight in the jungle, where he begged Steve to kill him. Steve refused to do so, and he opted to send Wo Fat to hospital instead, with prison officers guarding the room while Wo Fat lay handcuffed to the bed.
In the Season 3 finale episode, Aloha, Malama Pono, Wo Fat was seen lying in a bed in a High Risk Detention Facility at an unknown location with Steve standing in the room, staring at Wo Fat. At the end of the episode, Fat told Steve that he was his protection because the unknown forces currently breaking down Fat's door want Wo Fat dead, ending the episode in a cliffhanger.
In Aloha ke kahi I ke kahi, NLM terrorists sought to kill Wo Fat with McGarrett ultimately saving him. Later in the season, he escapes from prison. Later still, he rescues Lou Grover's daughter from Ian Wright.
Wo Fat returned in Ina Paha, having kidnapped Steve in the hope that Steve would break and tell Wo Fat what had happened to Wo Fat's own unnamed father.
During that time, Steve was held captive and given drugs, even going so far as to hallucinate an alternate reality where he was still a Navy SEAL, his father John McGarrett was still alive and that as a result of the Hawaii Five-0 Task Force never existing, Danny, Chin and Kono all leading different lives.
Back in reality, Steve later discovers that he and Wo Fat are brothers or presumably half-brothers given that Wo Fat grew up with Doris McGarrett.
Steve and Wo Fat also engage in a brutal fight that ends with Steve shooting Wo Fat in the head and thus killing him.
- Victor Hesse- (Deceased, killed by Wo Fat).
- Fred Durran- (Deceased, shot dead by Detective Danny Williams).
- Anton Hesse- (Deceased, shot dead by Lt. Commander Steve McGarrett).
- Sang Min- (Currently on the run, having escaped from prison).
- Wei Lyng- (Alive).
- Pao Dan- (Alive/imprisoned).
- Governor Pat Jameson- (Deceased, shot dead by Wo Fat).
- Haul Yorutt- (Deceased).
- John McGarrett- (Deceased, shot dead by Victor Hesse).
- Hiro Noshimuri- (Deceased, killed by Wo Fat).
- Wo Fat's Guard- Ki'ilua- (Deceased).
- Wo Fat's Commander- Ki'ulua- (Deceased).
- Wo Fat's Interrogator- Ki'ulua- (Deceased).
- Amilia Woods - (Deceased).
- Frank Delano- (Deceased, shot dead by Chin Ho Kelly).
- Brad Powers (alive/in custody).
- Unidentified Henchman/ driver/ sniper- (Deceased, shot dead by McGarret).
- Jenna Kaye (Deceased)
- Ian Wright - (Deceased, shot dead by Wo Fat)