¶1— Appeal by the defendant from a judgment of the County Court, Nassau County (Mackston, J.), rendered November 17, 1989, convicting him of robbery in the third degree, upon his plea of guilty, and imposing sentence.
¶2Ordered that the appeal is dismissed.
¶3The transcript of the plea proceeding reveals that the defendant knowingly and voluntarily waived his right to *929appeal as an essential condition of a favorable plea agreement. Accordingly, the issues sought to be raised by way of his motion to reduce his sentence and by way of his supplemental pro se brief are not properly before this court (see, People v Seaberg, 74 NY2d 1; People v Wittaker, 170 AD2d 554; People v Johnson, 158 AD2d 620). Mangano, P. J., Bracken, Kooper, Balletta and Ritter, JJ., concur.