Essex have given Tom Craddock and Tymal Mills two-year contracts which will run until the end of the 2013 season.
Leg-spinner Craddock, 22, impressed during a two-month trial period at Essex, in which he appeared 10 times.
Essex Coach, Paul Grayson said: "[Tom's] made a huge impact within the side and now I'm looking forward to working closely with him."
Teenager Mills, 19, moved through the ranks at Essex and has broken into the first team this year.
Grayson said: "We are hoping for bigger and better things from Tymal and he is a big part of the future at Essex."