Although the summer transfer window has closed, LaLiga rules allow clubs to register free agents provided there is space available in the squad.
Sevilla currently have all 25 slots filled, meaning a player must depart before Ziyech can officially join. Reports indicate third-choice goalkeeper Álvaro Fernández is likely to make way, with the club working quickly to finalise his exit.
Journalist Silvia Chaparros claims Sevilla and the 32-year-old winger have already reached an agreement, leaving only the registration process to be completed.
Ziyech, who is eager to secure a new challenge, recently left Qatari side Al-Duhail following a brief stint after his time with Galatasaray.
Before Sevilla emerged as frontrunners, the former Chelsea and Ajax star had been linked with a free transfer to Elche CF, with talks reportedly at an advanced stage.
In addition, Moroccan giants Wydad Casablanca had also expressed interest in bringing him back to the domestic league earlier this summer.
If confirmed, the move would hand Sevilla a creative boost, while offering Ziyech a fresh opportunity to revive his career in LaLiga.
Sevilla will welcome Real Madrid to the Ramon Sanchez-Pizjuan Stadium this weekend, with manager Luis Garcia Plaza anticipating a stern examination against one of European football's heavyweight sides.
Alaves boosted their La Liga survival chances by shocking newly-crowned champions Barcelona on Wednesday, while Getafe consolidated seventh position with a win.
Sevilla are up to 12th place in LaLiga's standings but still only three points clear of the relegation places after beating Espanyol 2-1 at Ramon Sanchez Pizjuan on Saturday.
Chidera Ejuke may have finally turned a corner in his Sevilla career, with his renewed intensity and work rate earning strong backing from head coach Luis Garcia ahead of their upcoming clash against Espanyol.
