The 30-year-old left-hander impressed at New Road in 2019, playing 14 games for the county in all formats of the game, hitting three centuries.
Rutherford told Worcestershire’s official website: “I am really excited to be returning to Blackfinch New Road for the 2020 season.
“I really enjoyed my two stints with the club last season and hopefully I can contribute to some success next year. I look forward to catching up with my team-mates and support staff in April.”
The left-hander, son of former New Zealand skipper Ken Rutherford, has played 16 Tests, four one-day internationals and eight T20 games for the Kiwis.
“Hamish is with us for the entire season which is really good for continuity,” said Worcestershire chairman Paul Pridgeon.
“He did well for us and we thought trying to sign him for the entire summer was worth persevering with. He is available for all cricket.
“Hamish was very keen to come back, he is enthusiastic and has gelled with the rest of the lads in the dressing room.”
The new-look Bob Willis Trophy has replaced the traditional Championship campaign in the wake of the Covid-19 pandemic.
Stokes produced a player-of-the-match performance with an unbeaten 84 as England won the Cricket World Cup last July.
The 64-year-old former England all-rounder backed Brexit and has now been awarded a peerage.
Clarke wants Surrey, who were due to welcome 2,500 fans into Kia Oval this weekend, to honour Bob Willis by winning the competition named after him.
Injury to his team-mate has given another Kent player a chance to impress.
The Johannesburg-born player stood out in the six-wicket loss to England in the ODI series opener at Southampton.
The campaign was meant to start in April.
England beat Ireland by six wickets on Thursday to take a 1-0 lead in the three-game ODI series
The Kent player sustained the issue during training on Wednesday.