Millwall have signed England Under-20 international Connor Mahoney from Bournemouth for an undisclosed fee.
The Sky Bet Championship club say the winger, now 22, has signed a long-term contract at The Den.
"I'm delighted to finally be here," Mahoney told the official Millwall website.
"I can settle down with the lads this week before heading off to Portugal on Friday, and hopefully this is the beginning of a long and successful career for me down here at Millwall.
"I'm an exciting player, exciting to watch. I work hard for the team and for the club, but also want to bring something different – quality on the ball, getting fans off their seats.
"They pay good money to come and watch us, so hopefully there's a successful season around the corner."
Mahoney becomes Millwall's fourth summer signing after earlier deals for Alex Pearce, Frank Fielding and Matt Smith.
Millwall finished 21st in the Sky Bet Championship last season, finishing one place and four points above the last relegation spot.
"Last season wasn't the best for the club, but I was speaking to the gaffer (Neil Harris) and he was telling me about the season before, in which we had a top-half finish," Mahoney added.
"I think that's our ambition for this season, finishing there, and then you never know what might happen."
Mahoney began his career at Accrington and made 21 appearances for Blackburn before joining Bournemouth in 2017.
He has also had loan spells at Barnsley and Birmingham, making 31 appearances for the Blues' last season, and won England caps from U17 to U20 level.
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