England youth global Onomah featured 10 times for Tottenham last season but made just five substitute appearances in the Premier League as he fell behind fellow academy graduate Harry Winks in the pecking order.
Spurs tweeted today that the midlands club, who were relegated from the Premier League in 2015, will be taking Onomah on loan for the duration of the 2017-18 season.
The England Under-21 worldwide is one of the best and most promising young players in England, and it may have come as a surprise to Tottenham fans when it was announced that the midfielder was leaving on loan for a club in the Championship.
Tottenham academy product Onomah, 20, impressed as England won the World Cup this summer with a series of mature displays as a box to box midfielder.
Villa manager Steve Bruce wants extra midfield players after Jack Grealish suffered a potentially long-term injury this week.
Coach Mauricio Pochettino has previously been unwilling to send Onomah out on loan despite interest from several Championship clubs last season and pleas from the 20-year-old, who said last month: "I have wanted to [go on loan], but I trust the gaffer".
"I can't wait to get started".
"I know that promotion is the aim and I am here to help us achieve that".
On the other hand, Aston Villa have been rather active in the transfer market this summer and have pilfered a number of players from Premier League sides.