I am the only freelancer at my company looking for some extra side jobs. I will not have anyone else at my company doing the work, nor on upwork.
As long as I tie my bank account and fill in my w-9 with my corporate information, is there any thing else I need to do to be protected under by corporate liability veil?
You might want to get in touch with somebody from your country who can legally answer that question for you, eg. a lawyer or a solicitor. I'm sure there are probably some lawyer folk around on these forums who could answer that question for you but Upwork themselves would say the same thing that I've said.
From my assumptions though, if you're already working at a company, any additional self-employed work (that's what freelancing is) wouldn't be covered under any corporate laws as it would be a separate entity from your company.