A teenage gatecrasher who stabbed university student Laa Chol in the heart at a party in a CBD apartment building has been found guilty of murder.

Although he confessed to knifing Ms Chol at the EQ Tower during a scuffle in July last year, the boy said he didn't intend to kill or seriously injure the 19-year-old student.

But the jury rejected the 18-year-old boy's plea of manslaughter, returning a unanimous verdict in the Supreme Court of Victoria on Friday.

The boy, who now faces life in prison, cannot be named for legal reasons.