Westwood joined Villa from Crewe last August and went on to make 30 Premier League appearances for the midlands outfit during the 2012-13 campaign.
"This time last year I was still on pre-season with Crewe and now I'm signing another contract at Villa, it's a fantastic feeling for me," the 23-year-old told the club's official website.
Villa confirmed last week that Benteke, scorer of 23 goals in all competitions for them in 2012-13, had handed in a transfer request.
Should the Belgium international depart, it could clear the way for June arrival Helenius to establish himself as Villa's main frontman.
But the Denmark forward - who has netted twice for his new club on a pre-season tour of Germany which Benteke, given extra time off until July 18, has not been a part of - is keen for the pair to play together.
Helenius, quoted by the Birmingham Mail, said: "We have not been given much information about why he is not joining us for pre-season, but apparently he has put in a transfer request.
"It is down to the club and player how they want to handle the situation.
"It is not something that I take much joy from even though it improves my chances.
"We need the strongest possible squad for the upcoming season and I was looking forward to being in the same side as Christian Benteke.
"In that respect it is sad what is happening around Benteke as he was definitely one of the players that I was looking forward to observing and learning from."
- Sports & Recreation
- Christian Benteke
- Nicklas Helenius
- Premier League