Davis came to the SUNS at the end of 2015 as a mature aged recruit, six seasons after he finished at West Coast.
The 28-year-old was a surprise packet in the 2016 season and was a solid contributor, playing 19 games and kicking 15 goals.
Playing predominantly as a forward in previous years, Davis will be hungry to maintain his spot in the senior team.
The official paperwork was lodged with the AFL on Thursday.