The board said Gregorski will lead the district until a permanent candidate is identified to replace outgoing Superintendent Lance Hindt.
Hindt announced his resignation in May amid accusations of bullying and plagiarism in his past.
SEE MORE: Katy ISD superintendent's resignation effective Jan. 1, 2019
Mr. Gregorski is a 26-year public school veteran, first teaching in the classroom before serving as an assistant principal, principal, and then assistant and deputy superintendent.
Allegations first surfaced in March when businessman Greg Gay accused Hindt of bullying him in junior high school to the point he contemplated suicide. The superintendent denied those claims.
In April, Hindt was accused of plagiarizing his doctoral dissertation at the University of Houston.
'I DID DUMB THINGS': Katy ISD superintendent apologizes for drawing negative attention to district
The board of trustees unanimously approved pursuing a defamation suit on Hindt's behalf on May 10, hiring law firm Feldman & Feldman to represent the embattled superintendent.
Experts tell Eyewitness News since Katy ISD is going forward with the lawsuit, the district would have to prove several things, including actual malice.