He will join Manawatu team-mate Aaron Smith at the southern franchise along with injured Otago halfback Josh Renton.
Japanese halfback Fumiaki Tanaka is not returning for another season.
Fairfax Media reported Hammington had signed with the franchise for a year.
At 1.70m and 75kg, Hammington is similar in stature to Smith and is quick around the paddock.
A former Wellington representative, Hammington also played for the New Zealand Colts in 2010, alongside Highlanders Luke Whitelock, Liam Coltman and Tom Franklin.
Hammington was part of the Chiefs last year, joining the side as injury cover.
Meanwhile, the path to Japan continues for the Highlanders.Highlanders analyst Andy Watts will join the Japanese national side for a short stint over the next month, helping the team in its internationals against Georgia and Wales.
He will return to New Zealand in time for the Highlanders pre-season before Christmas.
He will join former Highlanders coach Jamie Joseph, who is now coaching Japan.
Also heading to Japan are former strength and conditioning coach Simon Jones and Highlanders resource coach Ben Herring, both of who have signed contracts with Japan for the next three years.
New Highlanders coach Tony Brown will head to Japan at the end of next season, to assist Joseph in coaching the Japanese national side.
Highlanders utility back Richard Buckman is playing for the Panasonic Wild Knights in the Japanese league this season.
He is still contracted to the Highlanders for the next two seasons but is playing in Japan for his match fitness.
Buckman missed all of last season because of a dislocated shoulder in the first game of the pre-season.