A synonym for “professionally” could be “expertly”. When someone does something expertly, they do it with a high level of skill and proficiency, just as when they do it professionally. For example, “She completed the project expertly.” is similar in meaning to “She completed the project professionally.”
Another synonym is “competently”. This word implies the ability to perform a task well and in a manner that meets the standards expected in a professional setting. For instance, “He handled the situation competently.” is comparable to saying “He handled the situation professionally.”
“skillfully” is also a good synonym. It emphasizes doing something with great skill and dexterity, which is often associated with professional work. For example, “The artist painted skillfully.” is similar to “The artist painted professionally.”
“diligently” can be a synonym in some contexts. When someone works diligently, they work hard and with care, which is a characteristic of professional behavior. For example, “She studied diligently for the exam.” could imply a level of professionalism in her approach.
In conclusion, words like “expertly”, “competently”, “skillfully”, and “diligently” can be used as synonyms for “professionally” depending on the context. They all convey a sense of doing something in a manner that is characteristic of a professional.