Vice-President Aren Palik, speaker Esmond Moses and the 23rd Micronesian Congress also took their oaths.
In his swearing-in address, the president said "unity is our strength and prosperity".
He said unity inherently demanded careful attention and vigilance.
Before being elected to replace the outgoing David Panuelo, Simina was elected as senator at-large for Chuuk State.
Palik had been elected as senator-at-large for Kosrae State.
On March, 29 candidates contested the 2023 elections for 14 seats across Micronesia's four states of Chuuk, Pohnpei, Kosrae and Yap.
Panuelo lost his seat in Congress in the election.
