Unlike his more laidback and easygoing counterpart from the original book, Disney's version of Ratty is portrayed as stuffy and sophisticated. He also appeared with Mole as alms collectors in Mickey's Christmas Carol.
Water Rat was introduced by the narrator as "a bit stuffy but a really fine fellow." Ratty, as he is sometimes called by his friends, was having tea with Mole when he heard a knock on the door. It was the postman, who handed Ratty an urgent message from Angus MacBadger. Ratty knew that it means that Toad, another one of his friends, was causing trouble again by one of his manias. It was proven right when MacBadger told him and Mole about Toad's new Gypsy cart and a horse named Cyril Proudbottom. Rat and Mole managed to find Toad driving down the road after having just wreck a greenhouse with Cyril and the cart. Toad greeted his friends in a friendly manner and offered to "show them the world." Ratty turned down the offer and told Toad off for his behavior. Toad laughed at his friend's words and gave Ratty and Mole the slip as they tried to get him off the cart. As soon as Ratty and Mole caught up with Toad, they noticed that Toad was acting more strange than before, making pouting noises and bouncing on the road. Ratty knew right away that Toad has a new mania: a motor mania. Ratty and Mole guides the crazed Toad back to Toad Hall and locked him up in his own bedroom, hoping it would help Toad get over the mania. Unfortunately, Toad escapes and was caught in a stolen motorcar.
Ratty, along with Mole and MacBadger, were called to court as witnesses to the Toad case and heard Cyril's story about how Toad got the motorcar. Ratty and the others were completely shocked when Mr. Winkie accuses Toad for trying to sell him the stolen motorcar, which lead everyone to believe that Toad was guilty of the crime. Ratty and his friends tried to reopen the case several times in other courts but their efforts were in vain.
On Christmas Day, Ratty and Mole were saying grace for Christmas dinner and for Toad when the door opened to reveal what appears to be a little old lady fainting at his doorstep. Ratty and Mole were taking "her" by the fire when something heavy hit Ratty's foot, causing him to drop the person, who was then revealed to be Toad in disguise. When the trio heard a knock on the door, they figured it was the police, who came for Toad. Despite Toad's pleas, Ratty told him that he owes a dept to society and had the reluctant Mole let them in. But it was really MacBadger behind the door and he came in to tell the boys about his discovery of Weasels in Toad Hall with Mr. Winkie as their leader and bearer of the deed to the estate. Realizing that Toad was innocent all along, Ratty apologizes for misjudging Toad and agreed to help get the deed back to prove Toad's innocence to the law.
Ratty, Mole, MacBadger, and Toad rowed to a secret passage and kept Toad from blowing their cover when he attempted to shoot a night guard. Through the secret passage, they came into a room full of drunken weasels and Mr. Winkie asleep with the deed on him. Ratty and MacBadger had Mole get the deed by lowing him with a cloth rope. They almost succeed with the night guard, who found the secret passage, caught them and woke up Mr. Winkie. This lead to a violent chase for the deed. Ratty and the others managed to escaped with their lives and Toad with the deed. Having proved Toad innocent, Ratty, Mole, and MacBadger were prepared for a New Year and were proud of a new, reformed Toad. However, their celebration was cut short with a banging sound outside. They ran to the window to find Toad and Cyril riding an airplane, much to their dismay.
Ratty and Mole play the part of the Alms Collectors who ask for donations from Scrooge. The first time they ask for donations by Scrooge he refuses, the second time Scrooge happily accepts.
The water Rat appeared in both versions of the Mr. Toad's Wild Ride, in Disneyland and Walt Disney World. The Walt Disney World version was replaced by The Many Adventures of Winnie the Pooh. In the ride he has the same role he had in the film.