There are a number of commercial cleaning services in most major cities that you should be able to find fairly. A more important question is how to sort through your options and find the best one.
I use facility management services in London for all the cleaning and maintenance tasks involved in running my business. The company I use is called Simplicity Services, and I found them by asking business colleagues for recommendations. Asking for recommendations is one way to find commercial cleaning services.
You could also try searching on Google. Most well-established companies will have a web presence. Try narrowing down your search to the specific type of cleaning service you need – perhaps it’s office cleaning, grounds cleaning, or retail cleaning.