The 22-year-old Denmark international has joined for an undislcosed fee and becomes Villa boss Paul Lambert’s fourth signing of the summer following the arrivals of Aleksander Tonev, Leandro Bacuna and Jores Okore.
And Lambert is delighted to have completed a deal for Helenius and backed his new striker to be a success in the Premier League.
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"The opportunity will be there for him, as it will be for the rest of the lads, and he has all the attributes to go and take it.
"He wants to go and make a name and a career for himself and he's made a good start at Aalborg. It's a case of continuing to work hard and building on that and I believe he can.
"He's a good player and the potential is there for him to grow into the team and grow with the team. He'll definitely be able to give the team a hand."
Helenius netted 16 times in 33 league games last season, and he is hoping to thrive in English football alongside fellow attacking stars Gabriel Agbonlahor, Andreas Weimann and Christian Benteke.
He said: "This is a big opportunity for me, a big dream to play in the Premier League with a club with the history of Aston Villa and I'm very excited," Helenius said.
"I know we have a young team and I know we came through a test last season and got better as a team over the course of the campaign. I watched the game against Liverpool at Anfield and was very impressed by the way the team played.
“As we got more confidence in the game, we became better and better and won 3-1 with some great attacking football.
"In Gabby Agbonlahor and Andi Weimann, for example, we have good players who have great speed and energy and a real love for playing for Villa. You can see this and you can also see the strength and quality of Christian Benteke.
“It is really exciting to be a part of this and I'm looking forward so much to pulling on the shirt and getting to know my new team-mates.”