Swansea's recent form has dipped following Williams' ankle injury and his absence has seen the Premier League side lose three of the four games he has missed.
Williams has been ruled out of Wales' World Cup qualifiers against Macedonia and Belgium and Rangel is keen to see the Swans captain return for their home match against Gus Poyet's Sunderland on October 19.
"Ash is an important player for us. He has been a consistent and regular player for us week in, week out," he told the South Wales Evening Post.
"He will be fit when we come back. How many Premier League games did he play in a row without a rest?
"Ash has not had many injuries. Hopefully he will get back to full fitness, get back in the team and help us."
Despite the Swans slide down the Premier League table, Rangel has been quick to compliment Williams' replacement Jordi Amat.
The 21-year-old formed an all-Spanish centre-back pairing with Chico Flores against Southampton on Sunday and Rangel believes Amat has potential.
"I thought Jordi played well. He has been playing for the last few games and he's shown that even at his age that he's a top player," he added.
"He's not as strong as Ashley and his leadership is probably missing a little bit.
"But one is 29 and one is 21. You can't blame Jordi for anything because he has fitted in so well."