Park and Choi Soon-Sil coerced local firms to "donate" tens of millions of dollars to non-profit foundations that Choi then used as personal ATMs.
The scandal, which has focused on Park's relationship with an old friend now arrested for fraud, sparked nationwide protests and saw parliament vote to impeach the president last week.
Park stands accused of colluding with her friend, Choi Soon-Sil, to coerce local firms to "donate" tens of millions of dollars to non-profit foundations that Choi then used as personal ATMs.
"We came to believe that it is necessary to raid certain parts of the (presidential) Blue House," said Lee Kyu-Chul, a spokesman for the team of independent prosecutors on the case.
The team -- appointed by lawmakers -- has recently taken over investigations by government prosecutors who had sought to raid Park's office in October but were turned away at the gate.
Park's office has objected to any raid on the Blue House, citing a criminal code that bans any such action on state facilities deemed to be militarily important.
"We are making in-depth legal reviews to counter the argument by the Blue House over the rejection of the raid," Lee said, adding the officials were also planning to interrogate Park.
Park has formally been identified as a suspect in the criminal investigation -- a first for a sitting South Korean president.
Park is also accused of ordering aides to leak confidential state documents to Choi, who has no official title or security clearance, and allowing her to meddle is some state affairs, including the appointment of top officials.
The Constitutional Court is reviewing the validity of the parliamentary motion to impeach her -- a process that could take up to six months.
Park's legal team was set to submit her defence to the nine-member court later Friday.