Cardiff City have signed left-back Scott Malone from Millwall for an undisclosed fee and had a bid accepted for Rotherham striker Alex Revell.
The Bluebirds are believed to have fought off competition from Brighton, Birmingham and Borussia Dortmund for Malone.
Former England Under-19 international has signed a deal until June 2017.
"I'm very happy to be here and eager to get started," Malone told the club website.
"With my contract soon to expire at Millwall, I was looking for a new challenge; a few clubs were interested, but when I heard Cardiff City was one of them it was an easy decision to make.
"The manager didn't need to persuade me at all into making this decision, I wanted to come and be part of his plans."
Malone could make his home debut against Fulham on Saturday, 10 January, subject to international clearance.
The 23-year-old emerged from Wolves' academy to turn professional in 2009.
Former Burton and Southend defender Malone, who can also play on the left wing, is Cardiff manager Russell Slade's first signing of the January transfer window.
Malone joined Bournemouth from Wolves in 2011, moving for £150,000 following an initial loan spell, and then joined Millwall in May 2012.
Malone scored in the Lions' 2-1 win over Blackpool in August and has made 20 Championship appearances this season.
Striker Revell, 31, was signed by Slade in 2010 when the Bluebirds boss was manager of Leyton Orient.
The 6ft 3in forward, who has also played for Wycombe Wanderers and Swindon, has scored four goals in 26 appearances this season.
Chelsea striker Islam Feruz is also training with Championship side this week ahead of a potential move.