In 1986, everything came together for the Mets, and Darling was no exception. He finished with a 15–6 record and posted his career-best 2.81 ERA, which was third-best in the N.L. He also received the only Cy Young Award votes of his career, finishing fifth behind Mike Scott of the Astros. The Mets led the way most of the season, and their top four starters all received Cy Young votes. On May 27, Darling tied his career-high with 12 strikeouts in a five-hit complete game victory which, despite a poor April, raised his record to 6–0. He was good on the road but even better at home with a 10–2 record at Shea. His worst blemish was off the field when on July 19, he and teammates Bob Ojeda, Rick Aguilera, and Tim Teufel were arrested outside a bar in Houston, Texas for fighting with security guards (who were also off-duty police officers). All four were released in time for the following game. Darling and Teufel pleaded guilty in 1987 to a misdemeanor charge of resisting arrest, were sentenced to a year of probation, and were ordered to pay $200 fines. The probation period was cancelled by a judge one month later. The incident fed into the Mets' reputation as a rowdy crew that season, although Jeff Pearlman, in writing about the incident in his book "The Bad Guys Won" shows an irony that while for many members of the team, such an incident would have come as no surprise, the four players involved were among the few exceptions, and the scuffle was out of character for them, started when the normally placid Tim Teufel—being treated to drinks by the others to celebrate becoming a father—got more drunk than he ever had in his life and mouthed off to security guards who were looking for a fight. Despite the run-in, Darling was featured on the cover of the August 25 issue of Sports Illustrated.
The 1986 National League Championship Series was tied 1–1 when Darling started Game 3, but he pitched poorly and left losing 4–0. The Mets recovered to win both the game and eventually the series. Darling opened the World Series against the Boston Red Sox. He pitched extremely well in Game 1, allowing only a single unearned run, but lost a hard-luck 1–0 game to Bruce Hurst. With the Mets in danger of falling into a 3–1 series deficit, Darling started Game 4 and extended his 0.00 ERA to 14 innings as the Mets won easily, 6–2. After Game 6, Bill Buckner and the Sox bounced back in Game 7, scoring three early runs against Darling. Shaky into the fourth inning, Darling was relieved, but the Mets recovered to win their second World Championship.