Fran Kirby scored the opening goal after only two minutes and Sam Kerr netted a second-half brace, the latter a delightful chipped finish, to seal a third FA Cup for Emma Hayes's side and a third trophy of 2021.
Last season's FA Cup was interrupted, then postponed to this campaign due to the COVID-19 pandemic.
Chelsea began the game second to Arsenal in the league standings, having lost to them on the opening day of the season.
However, they got off to the best possible start when Kirby pounced on a defensive lapse by the Gunners defence, who failed to clear their lines, and hit the ball into the bottom corner.
Chelsea dominated the first half in front of almost 41,000 fans while Arsenal looked a shadow of the side who were so far unbeaten in all competitions this campaign. They were not helped by the absence of England defender Leah Williamson through injury.
The Blues were incredibly wasteful in front of goal, though, with Kirby having efforts saved by goalkeeper Manuela Zinsberger and Australia striker Kerr hitting the bar when clear through one on one.
Kerr made up for that miss shortly after halftime, however, when she ran on to a long ball and cut inside the penalty area, toying with defender Lotte Wubben-Moy before firing a low shot inside the near post.
Jonas Eidevall, in his first season as Arsenal manager, urged his side forward but they were always crowded out by the Chelsea defence who expertly marked key Dutch striker Vivianne Miedema out of the game. Arsenal failed to have a shot on target.
The result was sealed for Chelsea in the 77th minute when player of the match Kerr chipped the ball over Zinsberger from the right-hand side of the penalty area.
After making up for her misses in the first half, Kerr became the second Australian to lift the FA Cup after former Matilda Taryn Rockall who won it with Arsenal in 1999.
"It wouldn’t go in in the first half -– it could have been 4-0 or 5-0 but they defended well. We knew that if we kept pushing at some point they would go in and they did," Kerr told the BBC.
"I'm paid to score goals but our defence was amazing and it was a team effort – I can't wait to party!"
The match was played on the 100th anniversary of the English FA banning professional women's football in 1921. The ban lasted nearly 50 years until it was rescinded in January 1970.