The 19-year-old made his debut in Sunday’s 4-0 win away at Sporting Gijon.
Parejo spent the first half of the season on loan at Queens Park Rangers.
“I am very happy to have made my debut and I will work hard to have more playing time,” he told AS.
“We also must be happy because we won comfortably at a place that can be very difficult.”
“Of course we are aware that Barca are ten points ahead and we hope that they begin to feel the pressure,” he added.
“There is still a long way to go and we must believe that we have a chance because Barcelona slipped up after the international games.
“Juande has said to us that we have to stay on this path and that we are still growing.”