Rhodes, 21, who made his List A and T20 debut for Yorkshire in 2013, will go straight into the Essex squad for their game against Derbyshire on Saturday.
"He is highly thought of at Yorkshire but they are keen for him to get out and play some red-ball cricket," Essex head coach Chris Silverwood said.
"We are pleased he has decided to join the club."
Essex have signed all-rounder Will Rhodes from Yorkshire until the end of the County Championship season.