The 34-year-old club captain has made more than 200 appearances for the Dons since arriving in 2016, but his form has dipped this term, leading to speculation about whether his time as number one at Pittodrie is coming to an end.
However, Lewis has excelled in his last two games against Dundee and Hibernian, and Goodwin has told him he will have nothing to worry about if he can maintain that form.
"I had a very good chat with Joe just after training there – very informal – just congratulating him on the last couple of performances because without him we wouldn't have picked up the four points we did," said Goodwin.
"We were very lucky in the opening 20 minutes against Dundee and at the weekend he made two really good saves against Hibs.
"Joe has had a disappointing season, he admits that himself. He's big enough and strong enough to know these things happen and confidence plays a big part. But Joe is still relatively young in goalkeeper's terms.
"I said that to him today – you only need to look at what (Rangers goalkeeper) Allan McGregor and (Hearts and Scotland goalkeeper) Craig Gordon are doing at 40 years of age.
"Joe is a very fit boy and is in great shape.
"He's had a dip in form but he's shown in the last couple of games he's still a very good goalkeeper.
"I've been honest with Joe and told him there will be competition in that position next season. I am looking to bring in another keeper, not necessarily to replace Joe but someone to come in and really compete with him.
"In any position, you need to know there's someone there breathing down your neck.
"If he continues to play the way he did in the last couple of games, there will be no issue whatsoever going forward."