England under 21 international, Cleverley has joined on a season long loan from Manchester United. He scored 11 goals in 33 appearances on loan for Watford last season as he impressed on the left side of their mdfield.
Speaking about the addition on Cleverley, Roberto Martinez told the club's official website: "Tom is a very exciting young player and we are delighted he his coming to us.
"He can play in a number of positions and will provide us with some good new options, and add great competition to the squad.
"We have been watching him for some time and feel he is the right sort of player to join our squad; young, hungry, desperate to play for the club in the Premier League and to grow with us."
Argentinian under 20 international, Di Santo has joined on a permanent basis from Chelsea for an undisclosed fee, said to be in the region of £2 million.
Speaking about his move, the 21 year old said: "I am just happy that my future has been sorted out now. I can't wait to start training, meet all my new team mates and start fighting for my place in the team.
"Roberto Martinez has big ambitions for the club and he made it clear how much he wanted me to be here. When a manager is so positive about you, then it is an easy decision to make."
Whilst Martinez added: "Franco is an Under-20 international for Argentina," he said, "with great Premier League experience having worked at a club with the calibre of players of Chelsea, and also spending a hugely beneficial year on loan at an established club like Blackburn Rovers.
"We all feel that Franco can fulfil his potential at our football club and he'll bring a completely different dimension to our squad with his presence, technical ability and hard-work."
Perhaps the most surprise move of the day was that of Charles N'Zogbia who has remained with the Latics, and so will enjoy/endure at least another four months with the club.
Meanwhile, Guillermo Franco is expected to join the club on a free transfer once fitness worries are resolved. The former West Ham front man is able to move outside the window as he is a free agent.