The Turkish international started the game in midfield alongside Andres Iniesta and Sergio Busquets. The bearded winger made his sixth start since making his debut last month in the same competition against rivals Espanyol.
Luis Suarez found the back of the net on four occasions while Lionel Messi netted a hat-trick.
Turan provided the assist for Suarez in the 88th minute. The 29-year-old dribbled past two Valencia midfielders and slid the ball though to the Uruguayan international.
Messi and Andres Iniesta played their ninth Copa del Rey game tonight as Barcelona increased their unbeaten run to 29 games.
Barcelona 7 – 0 Valencia
Barcelona (4-3-3): 1. Ter Stegen 3. Piqué 5. Sergio 7. Arda 8. Iniesta 9. Suárez 10. Messi 11. Neymar 18. Alba 22. A. Vidal 24. Mathieu
Valencia (4-3-3): Ryan; Barragan, Mustafi, Santos, Gaya; Gomes, Danilo, Parejo; Rodrigo, Cancelo, Siqueira