The Irishman, who will also remain as Martin O'Neill’s number two with the Republic of Ireland, has been keen to make a return to the day-to-day workings of football since being sacked as Ipswich manager in January 2011.
Keane, despite previously being in charge at Sunderland, insists he has no problems being an assistant.
"From my experience so far alongside Martin I am a bit more hands-on with the players, which I have enjoyed," he said.
"It is a different role with Villa but I can adapt and I think my experience as a manager will help because it is tough being a manager.
"Hopefully I will make Paul's job easier. Hopefully I am someone Paul can trust; (I can) talk to the players and staff.
"I have some good experience from my playing days - some bad ones as well.
"I'll keep my job description pretty simple. I'm here to help the team and get results.
"I have some good experiences as a player and a manager and obviously he (Lambert) thinks I can bring something to the party.
"I am not promising miracles but hopefully an improvement."
Keane, who was linked with the Celtic job earlier this summer, revealed that it was the opportunity Villa offered-allowing him to remain in a position with the national team- which convinced him to make a return to the Premier League.
"I have thought about it. I've had three years off, I should be ready," he added.
"It was the whole package: that I know Paul, Villa is a top club, that I could continue working with the Irish team.
"You weigh all these things up and I kept coming up with the same conclusion.
"They (Villa) have had a difficult two or three years but that is part of the challenge.
"I am aware the club is for sale but that did not put me off.
"I have a chance to work with Paul at Villa: from a selfish point of view I think it would help me working with players in the Premier League.
"I am fortunate to be still working with the Irish team, I don't think it will be a problem working in the two roles."
I cant imagine many things worse than going into work every day with Keane's sour face and forthright often dodgy opinion for opinion's sake biting at your ankles. I will give Lambert, generiously, until Xmas before he decides 'it's him or me'. I am guessing the board, instead of admitting mistake, will choose Keane. And this will probably see them relegated. Keane has a habit of dividing the dressing room rather than uniting it. I also dont think there's a manager in the Premiership who Keane hasnt had a run-in with so that wont help if you do go in for transfers.- magicfuller