What you need to know:
- The 26-year-old midfielder is United's sixth signing since they finished second in the WSL and lost the FA Cup final to Chelsea last season.
Manchester United announced the signing of Spanish World Cup winner Irene Guerrero from Atletico Madrid on Thursday as the Red Devils target a first-ever Women's Super League title.
The 26-year-old midfielder is United's sixth signing since they finished second in the WSL and lost the FA Cup final to Chelsea last season.
Guerrero was a member of the Spain squad that beat England 1-0 in the World Cup final in Sydney last month.
"I feel very happy and very privileged to be here," Guerrero said.
"I am very proud to be part of the Manchester United family and look forward to achieving all our goals together."
United boss Marc Skinner said: "Irene is a World Cup winner whose quality is an excellent addition to our team.
"The experience she brings, both domestically and internationally, will be key as we pursue success across the multiple competitions, we face this season."
Skinner has overhauled his squad, bringing in the World Cup's top scorer, Japan's Hinata Miyazawa, Gemma Evans, Geyse, Emma Watson and Evie Rabjohn.
But United lost England striker Alessia Russo to rivals Arsenal on a free transfer and face a battle to hold on to star goalkeeper Mary Earps.
One of the heros of the Lionesses run to the World Cup final, Earps won the Golden Glove for being the best 'keeper at the tournament.
Arsenal have also been linked with Earps, who has one year left on her contract at United.