When Barry returned to work following his coma, Singh requested DNA evidence from him in regards to the Hotchkiss case. Barry promised to bring it right to him. Later that day, he sent Barry, Eddie Thawne and Joe West to the scene of a homicide.
At the scene of a robbery, although there only appeared to be one person, Barry determined that there was in fact six, all with the same shoe size, which he noted to funnily enough be the same as Captain Singh's, prompting him to apologize and reassure that obviously Singh was not a suspect. David and Detective Thawne promptly walked away. Later in the investigation, after the robber, identified as Danton Black, began shooting up a Stagg Industries warehouse, Singh and the rest of the department suited up to backup the two detectives already there.
Singh approached Barry looking for the "fiber analysis on the Orloff case". Barry told the captain that he'd finished it and promised to bring it down for him, though Singh was skeptical that Barry would be quick, so he decided to tag along behind, along with Caitlin Snow. He queried who she was and she claimed to be Barry's personal physician. As they reached his lab, Barry handed Captain Singh his findings and Singh surveyed the lab, telling him to clean it up (unbeknownst to him, Barry had used his super speed to put together the case file).
After a failed attempt to rob the Kahndaq Dynasty diamond, Singh was at the scene, where he was told by a guard there were three men involved. When Barry arrived, Barry corrected Singh that there were actually four men. After Barry gave his reasoning, Singh sarcastically thanked Barry for his insight.
Captain Singh is seen eating a burger and fries, telling Joe that his boyfriend (later fiancee) is trying to make him eat healthier and the precinct was the only place he could eat what he wanted. He later allowed an adamant and pushy Eddie Thawne to begin a task force against The Flash.
After the return of Leonard Snart, Captain Singh allowed S.T.A.R. Labs help out the police force, by designing an ice-proof ballistics shield. Cisco Ramon demonstrated the shield using a dummy, but Singh was skeptical that it would work well with real officers. A while later, Singh attended the scene of a fight between Captain Cold and Heat Wave, learning of the legitimate existence of the Flash. He attempted to stop Detective Thawne from helping out The Flash, but was unable to. However, Eddie survived and was rushed away from the fight by The Flash. Before long, the two men were stopped and handcuffed. They were led through the police precinct by Captain Singh, who had to help intervene when Rory accidentally came loose from the police escorting him.
Mark Mardon returned to get revenge for his brother's death. His outrage on Joe, causes Singh to put protective service on Joe. After Mardon attacks the police station, Singh is hospitalized trying to protect Joe from Mardon's attack, having taken severe physical and mental damage.
Later, when Barry accidentally went back in time by one day, he captured Mardon before he had a chance to attack the police station, preventing Singh from ever being hurt.
Singh, now having grown a beard, asks Joe about Al Rothstein's death. When asking about Cisco, the latter arrives, comments about Singh's beard and brings "the boot", a technology so the CCPD officers can now stop evil metahumans. After that, Singh tells Cisco that he wouldn't give him a badge.
When Zoom beat the Flash, he ran to the police station holding the Flash to show what had happened to their "hero". David, along with the entire police station, held Zoom at gunpoint. Singh ordered to open fire though he caught all the bullets with one hand, leaving everyone terrified.
Months later, Singh got a phone call from an unknown person. The person told him that he some needs information. Singh asked the person who is he, and he said that he is Green Arrow. Singh, who didn't believe him, asked for a proof. Seconds later, the Flash came into his office and put a note that says "HE'S LEGIT", before running away from there. Singh, realized he's really talking to Green Arrow, asked him what he wants to know. Green Arrow asked for information about Tina Boland, a former Police detective of the CCPD. Singh told him that after her partner, Vincent Sobel, got killed, she quit the CCPD and they haven't heard from her since. 
David takes his job as a police captain very seriously. He seems to believe Barry Allen to be sloppy and perpetually tardy, completely unaware of the reason why he is always late. During a case, he is typically very harsh and doesn't tolerate much of Barry's tardiness or light humor. In spite of this, he cares very much for those under him in the Central City precinct, going out of his way to assist them in any way if they get into a pinch, diverting the resources at his disposal if he must, as seen when he strongly recommended Joe to stay in close protection when Joe was being targeted by a meta-human and later took a hit (from a lightning bolt) for him when Mardon came to kill Joe, and before that, he even instructed Joe to have Iris contact the Flash for assistance; he also pleaded with the district attorney when Eddie was accused of shooting two police officers. It is revealed by David's boyfriend that he actually respects Barry and speaks quite highly of him, also stating that David "is all bark. A really loud bark".
Despite his serious personality, David does have a romantic side. He mentions that his boyfriend is trying to encourage him to eat better. In "Out of Time", he mentions that they are now engaged, suggesting he is more than capable of maintaining a relationship as well as handling a case. After being married for over six months, David has been shown to have matured somewhat, showing a less abrasive side to others. He has also come to express extreme trust in the Flash's heroism, intentions, and has come to deeply respect the Scarlet Speedster.
David's tough exterior seems to function as a coping mechanism given his extremely stressful line of work and his responsibilities as a Captain. During Hannibal Bates's crime spree he talks to Barry who is concerned for the Captain's stress levels in the tone of a peer and equal, giving Barry a look into the man behind the badge, improving their personal and working relationship significantly, as evidenced by their lack of conflict beyond that point.
Despite being a police captain, David can be quite gullible, this is evidenced by the fact that when Clifford and Marlize DeVoe (who appeared to be nice people) claims that Barry was harassing them for no apparent reason (in truth he was simply investigating them) he unfairly suspended Barry from the CCPD without hearing his side of the story first, despite this, the two do still seem to be on good terms with each other, as he was still invited to attend Barry and Iris' wedding and he spoke favourably of Barry in the latter's trial.
- "The Scientist" (mentioned)
- "All for Nothing" (flashback)
- "Stretched Scene #2" (name on screen)
The Flash: Season Zero
- In a second erased timeline David, presumably, along with everyone in Central City, was killed by Vandal Savage using the Staff of Horus in his efforts to kill Carter Hall and Kendra Saunders. However, due to Barry Allen changing the time continuum this disaster never occurs.
Behind the scenes
- In the DC comics, David Singh is the director of the crime lab at Central City Police Department, who takes Barry Allen into his lab on Captain Frye's orders.