The 43-year-old scored over 24,000 runs during 12 seasons at Hove, and helping them win three County Championship titles and four limited-overs trophies.
"I am grateful for the opportunity to come back to my second home," he said.
"I believe I can bring to a very talented squad some belief and options on playing certain situations in all formats. I'm hoping to try and add a winning culture."
Sussex have reshuffled their coaching set-up following relegation from Division One last season and cricket manager Mark Robinson's appointment as head coach of England Women.
Mark Davis was appointed head coach in November, with Keith Greenfield named director of cricket and Carl Hopkinson now academy director.
Davis said he was "thrilled" to see former Zimbabwe international Goodwin, who left Sussex at the end of 2012 to join Glamorgan, back at Hove.
"I am confident Murray's relentless approach to batting and his technical expertise will be of great value," Davis added.
"He has a brilliant work ethic and a passion for teaching the game, which is a vital ingredient in any elite coach."
Sussex have appointed ex-player Murray Goodwin as their new batting coach.