England winger Rachel Yankey scored two goals as Arsenal lifted the Continental Cup to complete the treble with a 4-1 win against Birmingham City Ladies.
Ellen White and Jayne Ludlow fired the Women's Super League and FA Cup winners into a first-half lead.
Yankey struck twice either side of a Isobel Christiansen goal for Birmingham, who had striker Rachel Williams sent off in stoppage time.
"To win in style was a massive positive," said manager Laura Harvey.
"We knew it was going to be tough against a Birmingham side who are always looking to get the ball into your penalty area.
"We started the game badly, but we defended well throughout and the only real hiccup was their goal."
Harvey's team almost went behind in a scrappy opening period, midfielder Jo Potter firing a 30 yard free-kick just over the bar after 15 minutes.
The deadlock was broken in the 26th minute when Katie Chapman's 20-yard drive was deflected into the path of White for the striker to score from 10 yards.
Birmingham failed to regroup from the restart and a minute later captain Ludlow was allowed time and space to head home striker Danielle Carter's looping cross.
Blues hit back and either side of half-time Arsenal goalkeeper Emma Byrne had to make goal-line saves, first from Williams then her strike partner Jodie Taylor.
The all-important third goal arrived 20 minutes into the second half for the Gunners, Yankey's 25 yard free-kick deflecting off the defensive wall to loop over goalkeeper Marie Hourihan.
A late fightback looked possible when substitute Christiansen, with her first touch, bundled the ball in after Byrne had dropped Karen Carney's cross.
But there was no way back for Blues after Yankey had hit the goal of the match, a superbly struck 20-yard volley which flew into the roof of the net six minutes from time.
Williams, who had been booked for a 54th-minute challenge on Ludlow, received her marching orders after pushing central defender Gilly Flaherty in the chest.
Former Arsenal player Carney, devastated at her team's defeat, said: "It was such a disappointing way to end the season.
"We finished runners-up to Arsenal in the League and now the Cup - people have been saying we've had a great season, but it's not great if you've won nothing."