The Jenner Racing driver grabbed the lead from pole position and never relented at the front to control the race and take her third win from three races in 2022 and fifth in a row counting back to the end of the 2021 season when she clinched her second W Series crown.
Racing X's Abbi Pulling piled on late pressure, fending off Alice Powell at the same time, but had to settle for second place with any overtaking proving very difficult at Circuit de Barcelona-Catalunya.
Chadwick got the ideal getaway to convert pole position into the race lead, while Pulling used the grippier side of the gird to her advantage to bolt into second place ahead of Click2Drive Bristol Street Motors driver Powell, with Emma Kimilainen pulling off the same feat on Beitske Visser into the first turn.
The race largely settled down in the early stages with all drivers wary of maintaining tyre life in the scorching temperatures in Barcelona.
It led to a trade-off in fastest lap times between the top three who gradually eased away at the front, with Chadwick maintaining a half-second margin over Pulling.
But with tyre and temperatures limiting the pace for all runners, Chadwick was able to keep her lead bouncing between 0.5s and a full second on Pulling, with Powell facing the same deficit back in third place.
To Pulling's credit, she put on sustained late pressure over the final two laps but couldn't force an error from Chadwick who stormed to victory to continue her perfect start to the 2022 W Series season.
Pulling and Powell completed the podium for an all-British rostrum, comfortably ahead of Kimilainen who had a lonely race to fourth place after breaking clear from Visser.
Marta Garcia grabbed sixth place for the CortDAO W Series team in her home race, ahead of fellow Spaniard Belen Garcia for the Quantfury W Series squad.
Fabien Wohlwend finished a distant ninth place for CortDAO W Series, as Sarah Moore completed the top 10 for Scuderia W after passing Jess Hawkins midway through the race.
The 2022 W Series campaign resumes at Silverstone as part of the F1 British Grand Prix support card on 1-3 July.
