It also revealed Bell's co-worker Karan Poole was also quitting with her.
"As you may have noticed I'm not in work today," the note began.
"This is because you are a***holes to work for so I have got a new job.
"I was planning on giving you a week's notice but whilst I was on my unpaid break, (name removed) radioed (name removed) to come tell me not to sit down on my break.
"Why not grow some balls and tell me yourself?
"Because that would mean you getting off you're a*** and leaving the office!
"I hate the fact that even whilst on my unpaid break (name removed) sat in his office spying on me.
"Maybe if you two worked constantly, on your feet for six hours you also would like to be able to sit down for ten mins!
"Regards, Lisa Bell.
"P.S. Karan quits too, you've treated her even worse … we're off to work together."
The mother-of-one shared pictured of the card on social media, describing her boss as a "bully" in an accompanying caption.
Speaking with the Manchester Evening News after posting the card online, Bell said the "awful" job left her "at the end of my tether".
"I bought the card on Tuesday and posted it first class, knowing they'd receive it on the Wednesday," she told the publication.
"They've lost two good cleaners — reliable and hardworking. I'm quite a bubbly and outgoing person. Luckily my new boss has got a sense of humour."
Bell claimed she had to sneak into the toilets for water as staff weren't allowed to drink on the job, and there were no chairs provided in the staff smoking area.
She also said staff were "on camera constantly" and the bosses were "watching".
Lyndene Hotel has issued a statement on social media regarding Bell's claims.
"We are disappointed to read Lisa's comments regarding her time with us and regret that she felt unable to speak to the management of the Lyndene directly to address these issues," the statement reads.
"We would welcome the chance to discuss the matter with her privately and listen to her concerns regarding the time she spent as part of our team.
"We wish Lisa success in her next role and will not be offering further public comment on the matter."