The part of a sentence "I previously worked" is correct and usable in written English.
You can use it when you want to express that you had a job in the past. For example, "I previously worked as an accountant for 5 years before switching to a new job."
I previously worked for the NHS and in education.
I previously worked for a large printing company in Scarborough.
SETTLEMENT HOUSE I previously worked for a company run by a genuinely bad boss.
(In addition to editing his posts for Economix, I previously worked as one of his research assistants while an undergraduate at Princeton).
Before setting up Chemist Direct, I previously worked as a management consultant, working with Citigroup, Deutsche Investment Bank, SAP and Deloitte Consulting.
I previously worked for a medical education company where all concepts and strategies belonged to the funding sources that paid the employees' salaries.
Nevertheless, as more people proposed the networking concept to me, I began to think of women I had previously worked with who knew I was driven and reliable.
I knew these things before I took the job: I had previously worked a shift at the warehouse-sized gallery after a guard called in sick.
I was lucky: Curtis Briggs, an associate of Serra's I had previously worked with, was angling to bring Chow on as a client.
(At the time of applying I was in a short-term contract as a business analyst, and I had previously worked part-time in my father's company in market analysis).
When I became private chef to [retail and property magnate] Charles Clore, it was a shock, as I'd previously worked for rich people with lots of manners, but there was a lack there, especially as it was during the time of his divorce.
