The LottoNL-Jumbo sprinter won the final stage in last year's Tour and it took seven days into the 2018 edition for the 25-year-old to win another.
He finished ahead of the only two sprinters who have taken wins so far at this year's Tour, Fernando Gaviria (Quick-Step Floors) and Peter Sagan (BORA-hansgrohe).
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The general classification was pretty much unchanged as the key players sat in and left it to the domestiques to push the wind out of the way and the sprinters to take the glory.
Greg van Avermaet (BMC) now leads Geraint Thomas (Sky) by six seconds after a raid on the bonus sprint and Tejay van Garderen sits 8 seconds back.
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The stage got started with the first attack coming from Thomas Degand (Wanty-Group Gobert) but he soon decided he was not game to go it alone on what was the longest day of the 2018 Tour.
Another attempt to break free came after 20km of racing but this time it was a strong group of 10, including Oliver Naesen, Tony Gallopin (both AG2R-La Mondiale), Thomas De Gendt (Lotto-Soudal), Arthur Vichot (Groupama-FDJ), Lukas Pöstlberger (Bora-Hansgrohe), Yves Lampaert (Quick-Step Floors), Michael Gogl (Trek-Segafredo), Julien Vermote (Dimension Data), Edward Theuns (Sunweb) and Simon Gerrans (BMC).
There was no way an assembly of that standard would be allowed any leeway by the sprint teams and a concerted chase from Lotto NL-Jumbo ensured that they were soon reeled in only five kilometres later.
Wanty-Group Gobert then returned to the front of the race with another solo rider, this time Yoann Offredo, who seemed to have the legs and bravery to settle in for a long solitary dig.
Offredo's lead on the peloton passed eight minutes as he turned over the pedals at 38km/h but that would be the high point as his time at the front slowly ebbed away.
There was a split in the peloton orchestrated by AG2R La Mondiale across a flat open section which placed Stage 6 winner Dan Martin (UAE Team Emirates) in some danger. But they eventually stepped on the gas to close it down, in the process ending Offredo's lonely exploit.
That effort over, the peloton settled to a pace much slower than the expected arrival time until Laurent Pichon (Fortuneo-Samsic) escaped with 84km to go eventually earning him the jury award as the day's most combative rider.
Pichon scooped up the 20 points on offer at the intermediate sprint at Berd’huis with Fernando Gaviria (Quick-Step Floors) second ahead of Peter Sagan (BORA-hansgrohe).
The stage picked up with 38km to go when Pichot was caught and teams with a sprinter on the roster took control at the front.
Van Avermaet then surprised to take a cheeky three seconds at the bonus sprint at Nonvilliers-Grandhoux - 30km from the finish - slightly extending his overall lead.
From that point on it was all about the sprinters. A messy finale again saw Quick-Step Floors position Gaviria at the front to launch his sprint.
While the Colombian got a good jump, it was Groenewegen who came from behind with too much pace, beating the two-time stage winner by a few bike lengths in an emphatic victory.
Sagan stayed in Gaviria's wheel to take third and keeps the points jersey into Stage 8, and none of the other jerseys changed hands.
