Frederick, 22, was let go by the Alberton club at the cessation of the 2022 season following 14 appearances in silver, teal, black and white.
Originally joining Port Adelaide via the club's Next Generation Academy, the Adelaide-born talent of South Sudanese heritage will stay close to home, joining Marty Mattner's Double Blues squad at Unley Oval.
The agreement will see the rebounder return to the level, with Frederick having tasted SANFL premiership success with Woodville-West Torrens' under-18s during his draft year of 2018.
“We're delighted to have Martin join the club,” Sturt Football Manager Chris Trap said.
“He has elite speed and power and will add an x-factor to our lineup.”
Though the ink has dried on the deal to bring him to Oxford Terrace, reports from The West Australian arose last week, announcing that Frederick had made his way to WA in an effort to sound out a future in the WAFL.
This proposed shift held added weight given Frederick's twin brother, Michael, is a blossoming member of Justin Longmuir's Dockers roster.
2022 proved a season of some promise for Sturt, finishing fifth after the home-and-away season before being edged out by Glenelg on elimination final day.
Emmett, a forward made in the ilk of St Kilda's Tim Membrey, joined Ashley Johnson (Collingwood), Jed McEntee (Port Adelaide), Charlie Parker (Western Bulldogs) and Tex Wanganeen (Essendon) in making the leap.