Nonu's final chance of securing a Super Rugby contract in New Zealand now lies with the Auckland Blues after the Otago Highlanders, Canterbury Crusaders and Wellington Hurricanes all passed up the chance to sign him.
Local media reports this week said the Blues were talking to Nonu, although a decision is not expected until after the third Bledisloe Cup test against Australia in Dunedin on Saturday.
Super Rugby squads need to be confirmed by the end of the month.
Nonu's playing future has been a concern for the New Zealand Rugby Union (NZRU) this season after he walked away from a contract extension with the Highlanders, a year after joining them from the Blues.
He joined the Blues for the 2012 Super Rugby season after being told by Hurricanes coach Mark Hammett in 2011 that he was not in his future plans.
After it had become clear the inside centre was not returning to Dunedin and he expressed a desire to return to his home town, Nonu met with Hammett but the Wellington-based franchise did not offer him a contract.
The NZRU has become increasingly resigned to Nonu playing offshore in the first part of 2014, creating selection issues for All Blacks coach Steve Hansen due to the policy which restricts the national team to players contracted to New Zealand-based sides.
The Chiefs had been interested in coaxing Sonny Bill Williams back from rugby league but when he committed to another year in Australia, Nonu's name had been mentioned as a possible, though unlikely, candidate for a move to Hamilton.
Friday's announcement ended that possibility with the Muliaina and Fruean completing the Chiefs' squad for next season.
World Cup winning All Black Muliaina, 33, has returned from two years in Japan, while Fruean was off contract from the Canterbury Crusaders following heart surgery earlier this year.
"I am thankful for the chance to return to rugby at this level and am really looking forward to the Chiefs environment and the beginning of a new and important chapter for me," Fruean said in a statement.
The Chiefs will be seeking a third successive Super Rugby title next season and coach Dave Rennie said he thought both players could play important roles in the campaign.
"Mils and Robbie are both proven talents and top men," he said.
"We know the value they will add to our side. Robbie is big and powerful and Mils is one of the most experienced players in New Zealand rugby so both are great additions to our squad."