The 60-year-old, who stepped down last month after 23 years in charge of the New Zealand men's sevens side, and following their quarter-final exit at the Rio Olympics, has been appointed Samoa's new coach.
Tietjens, who led New Zealand to two World Cups, four Commonwealth Games gold medals and 12 World Series crowns, will have former Manu Samoa coach Stephen Betham as his assistant.
"Samoa has huge amount of potential to start progressing in the World Series," he said.
Sir Gordon was due to take up his new role in January but expected greater consistency from his new side from the outset of the World Series in Dubai in December, he said.
He would also implement a coaching structure and plan for up-and-coming coaches in Samoa.
Samoan prime minister Tuilaepa Aiono Sailele Malielegaoi, who is also the chair of the Samoa Rugby Union, said: "In trusting our sevens team to Sir Gordon, we believe we have a coach who understands how important rugby is to our people, and he has a deep appreciation of how to get the best out of the talent we have."
The length of Tietjens' contract was yet to be negotiated but was likely to be two years.
Photo: RNZI/Autagavaia Tipi Autagavaia