Kurt Zouma in action for West Ham (AFP)
The 27-year-old France international has apologized for kicking and slapping a cat in abuse caught on video and posted on social media.
Wages weren't disclosed but British media reported the fine to be over $300,000.
The Royal Society for the Prevention of Cruelty to Animals took custody of Zouma's two cats while it investigates the incident.
"Kurt and the club are co-operating fully with the investigation and the player has willingly complied with the steps taken in the initial stage of the process, including delivering his family's two cats to the RSPCA for assessment,'' the Premier League club said Wednesday.
"Kurt is extremely remorseful and, like everyone at the club, fully understands the depth of feeling surrounding the incident and the need for action to be taken,'' West Ham's statement added.
The club said that apart from the RSPCA's investigation "and pending further sanction once the outcome of that process is determined'' it has fined Zouma "the maximum amount possible'' _ which is two weeks' wages.
"The player has immediately accepted the fine and has requested that it is donated to animal welfare charities,'' West Ham said.
The club reiterated "our condemnation of Kurt's actions'' and said the matter is being handled "with the utmost seriousness.'' It added that it won't comment further at this stage while RSPCA investigates "in a fair and thorough manner.''
The RSPCA confirmed on Wednesday, amid growing public calls for Zouma to be prosecuted for animal cruelty, that it has custody of the cats.
"The two cats are now in RSPCA care. Our priority is and has always been the well-being of these cats,'' the organization said in a statement. "They've been taken for a check-up at a vet's and then will remain in our care while the investigation continues.''
Zouma started for West Ham in a 1-0 victory over Watford on Tuesday night, hours after the club had initially condemned the defender's actions.
The RSPCA said it was "grateful to everyone who expressed their concern for these cats. We were dealing with this issue before the video went viral online and are leading the investigation.''
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)