The winger has joined for and an undisclosed fee and has signed a three-year contract. He will take the number 19 shirt.
Ajiboye came through the youth ranks at Brighton before joining Sutton and went on to make 126 appearances for the club, scoring 17 goals.
Grant McCann said: “David has pace to burn, he can play wide on the right or left, he brings something different to what we already have. He is very direct, he will take people on and put teams on the back foot.
“The different variations to our forward line is what we like, he is a very hard-working wide forward and will put a huge shift in for the team out of possession with his counter press and reactions. He has been the standout player at Sutton and at League Two level and we believe this is the perfect progression for him to show his ability and we are delighted to have him on board.”
Ajiboye added: “I had three good years with Sutton and I am very thankful to everyone at the club for the opportunity. I felt like this was the right time for the next chapter and I believe this is the perfect place for me. I like to attack, get past the full-back, create chances and score goals.
“This club have had a lot of really good attacking players and there is some really good players here now and I can’t wait to get started. There has been a bit of talk about this move for a little while so I am really happy we have got it over the line.”