England striker Alessia Russo has joined Arsenal on a free transfer following her departure from Manchester United this summer.
Russo, 24, rejected several contract extension offers from United and left the club after three years.
"I want to win trophies - as does everyone in this club," said Russo.
"I can't wait to get stuck in and grow as a player. It's a new challenge and a new environment.
"I think the growth of the women's game has been incredible, but particularly at a club like Arsenal.
"The sell-out against Wolfsburg at Emirates Stadium last season was fantastic. I'm just really excited to be part of this club."
The Euro 2022 winner, who is in the England squad for the Women's World Cup later this month, becomes Arsenal's third signing this summer following the arrivals of defender Amanda Ilestedt from Paris St-Germain and striker Cloe Lacasse from Benfica.
Russo joined United in 2020 under former manager Casey Stoney following two years in the United States at the University of North Carolina.
She was United's joint-top scorer in the Women's Super League this season with 10 goals and one assist in 20 matches as they finished runners-up in the league - their highest ever finish, which ensured qualification for next season's Champions League.
The centre-forward was a breakout star at Euro 2022, coming off the bench to score four times, including a memorable backheel in the semi-finals, as England won their first women's major tournament.
There is competition in the Arsenal squad for attacking positions with England's Beth Mead, the Netherlands' Vivianne Miedema - both recovering from anterior cruciate ligament injuries - Australia's Caitlin Foord and Swedish pair Stina Blackstenius and Lina Hurtig already on the books.
Russo will join her Arsenal team-mates after the Women's World Cup, which kicks off in Australia and New Zealand on 22 July.
The new WSL season starts over the weekend of 29 September to 1 October.
'Russo strengthens Arsenal's squad' - analysis
BBC Sport's Emma Sanders
This is a blow to United, who hoped Russo would sign a contract extension but instead lose her to a WSL rival.
It strengthens Arsenal's squad depth - which they relied upon so heavily last season when an injury crisis hit them on their way to the Champions League semi-finals.
Russo has proven herself as a goalscorer in the WSL and on the international stage but, while she was the undisputed first-choice striker at United, she will have to compete for a place at Arsenal.
That should help her development to have competition, which she is starting to get used to at England, and it will increase with the return of Arsenal's injured stars.
Arsenal have invested in their squad under manager Jonas Eidevall in an attempt to stop Chelsea's WSL dominance and this latest addition will help them to do that.
