Marcel Risse gave the hosts a deserved lead, before Anthony Modeste double that just after the hour mark to seal a very comfortable three points.
Fast start pays dividends
The Billy Goats began with a high-pressing, high-pace style that represented the anticipation fans had coming into the game. Michael Esser was forced into an early save from Leonardo Bittencourt's one-on-one opportunity, with Artjoms Rudnevs smacking the base of the post just moments later.
Darmstadt were on the ropes for the opening 15 minutes and after Modeste had rippled the outside netting, it wasn't long until Risse found the goal they had been hunting. Some more wonderful work from Bittencourt saw the midfielder turn and cross towards his fellow winger, who rifled under the helpless Esser.
After that, the game calmed down somewhat. Alexander Milosevic had the Lilies' only real sight at goal, even then it was a hopeful backward header that landed on the roof of the net. In turn, Bittencourt continued to lead the attack in what was a menacing display of wing play, as Köln tried and failed to convert several breakaways.
Thunder, lightning and Modeste
The second half followed on in the same vain as the first, with Esser putting in a commendable performance on his Bundesliga debut. He made a superb stop from Bittencourt to deny him a deserved goal, though the winger went close minutes before and Jonas Hector's cross evaded the outstretched Rudnevs in the aftermath.
Köln continued to come forward with real verve and, despite a breaking due to the weather closing in, they killed the game off after the 10-minute break. Modeste was on hand to tap in from Rudnevs cross, as the forward happily tucked home what he and the home faithful will be hoping is the first of many this season.
Late on, Darmstadt did begin to threaten more and none more so than Sandro Sirigu. The substitute made a powerful run right through the Köln midfield and defence, before curling a shot at goal. Luckily for the Billy Goats, Timo Horn was back from Brazil to make a timely save.
The only negative was a late injury to Dominic Maroh, and he was later confirmed to have broken two ribs following a collision with Esser. That aside, a very promising start to the season for Köln. As for Darmstadt, it looks like Norbert Meier has his work cut out this campaign.