Fisher, though, made it clear that his lineup can change before the start of the regular season.
Iman Shumpert is also vying for the starting shooting guard spot, but the coaching staff decided to sit Shumpert on Wednesday due to a hamstring injury.
Shumpert is expected to practice Thursday and be available to play for the remainder of the preseason.
Fisher said his decision to start Smith over the other candidates at shooting guard had to do both with injuries to Hardaway Jr. (hip) and with Smith's impressive play in training camp.
"J.R. has been consistent in practice, his work ethic has been great," Fisher said. "He's picking up the system as well as you possibly can expect a guy in the first week or so."
Smith has started and played off the bench in his Knicks tenure. He finished last season in the starting lineup, shooting better than 43 percent from beyond the arc in the final 20 games.
Smith was asked before Wednesday's game if he'd prefer starting or coming off the bench this year.
"Whatever they need me to do," he said. "This is a culture and a situation ... they've had much success in it. I trust in them that they'll make the right decision."