I believe you are thinking of the Rogue Wizard series, by Christopher Stasheff. The timing is about right (1993-2001) although the original book in the series was written much earlier (1979).
The protagonist's real name is Magnus d'Armand but most of the time he goes by his pseudonym Gar Pike, in order to minimize the risk of his activities causing trouble for his family. As you say, he wanders the galaxy protecting the innocent and overthrowing oppressors. You might also remember his possession of various Psi powers, though he usually tries to avoid using them until it becomes absolutely necessary to do so.
In the first of the newer books, A Wizard in Absentia, Magnus is alone. This is a prequel and comes first in terms of the in-universe chronology. It is followed by the original A Wizard in Bedlam at the end of which he acquires a companion.
There are ten books in the series in all, and the storyline is concluded in The Warlock's Last Ride from the related Warlock of Gramarye series.