The 24-year-old midfielder became the fifth most expensive sale in club history when he sealed his move to Tyneside on Sunday evening.
Villa will receive an initial £39million, with the potential of a further £5m in add-ons.
Ramsey will be followed out of the door by Dendoncker, who is close to joining Real Oviedo.
Villa are prepared to let the Belgium international leave for nothing, three years after he joined from Wolves for £13m, in order to lower their wage costs.
Bailey is also expected to depart, albeit initially only on a temporary basis with talks over a season-long switch to Roma having continued over the weekend.
That move will also free up room on Villa’s wage bill and potentially allow them to pursue a loan move for Marco Asensio over the final fortnight of the transfer window.
Ramsey left having made 167 appearances in all competitions for the club he first joined aged six.
The Birmingham-born star posted an emotional message on social media, in which he said it was “impossible to put into words” what playing for Villa had meant for him.
Ramsey wrote: "From being a young fan in the Holte End to living my dream and scoring in front of it. This club has been an extended family to me and I've got memories for life - from making my Premier League debut, experiencing Champions League nights back at Villa Park and scoring my first goals in those competitions.
"To everyone at Aston Villa, both at the academy and in the first team, thank you for your support, belief and guidance.
"You've helped me become the person and player I am today. I've played with some of the best and made friends for life.
"Finally, to the fans, thank you for the love and backing. To represent you, as a boy from Birmingham, has been an absolute honour.
"Onto the next chapter now but wish you all nothing but the best for the future. Thank you for everything!"