The Armenian, who arrived at Signal Iduna Park from Shakhtar Donetsk earlier this summer, has recovered from the ankle injury that curtailed his pre-season preparations
The Armenia international sat out last weekend's Bundesliga opener against Augsburg with an ankle injury sustained in pre-season but the summer signing from Shakhtar Donestk is available for selection.
"Henrikh is part of the squad," Klopp confirmed at a press conference on Friday. "Before yesterday, we had a 70-minute game amongst ourselves.
"He looked better and more sure of himself from minute to minute. He looked fairly decent."
Mkhitaryan, who is Dortmund's record purchase at €27.5 million, was signed to replace Mario Gotze, who departed for Bayern Munich earlier this summer, but Klopp was reluctant to compare the two players.
"He's a very good player, but a different type of player [to Gotze]."
Dortmund's meeting with the newly-promoted Eintracht Braunschweig is scheduled to get under way at 17:30CET on Sunday.