Short answer. Yes, but only after the guardianship itself has ended and the guardian has cleared any financial accountabilities owed to the ward. A guardian who wants to adopt their ward cannot file while still acting as guardian; the guardianship must first be formally terminated and the accounting settled.
What the law says
The guardian with respect to the ward after the termination of the guardianship and clearance of his/her financial accountabilities.
RA 8552, Section 7 — Who May Adopt. Read the full provision →
Guardians may adopt, but only after guardianship ends
The law names the guardian, with respect to their ward, as one of the persons who may adopt — but only after the termination of the guardianship and clearance of his/her financial accountabilities. A guardian is someone appointed to manage a minor's person or property, and that role naturally involves handling the ward's money, property, or both. Before that same guardian can step into the very different role of adoptive parent, the guardianship has to be formally ended and any accounting of what the guardian handled on the ward's behalf has to be settled. And if the former guardian is married, the general rule that husband and wife adopt jointly applied here as well — a ward was not among the situations the law excepted from joint adoption by spouses.
Why the accounting comes first
Requiring the guardian to clear financial accountabilities before adopting exists to prevent a guardian from using adoption to avoid answering for how they managed the ward's property or funds. Once the guardian becomes the adoptive parent, the ward's legal identity changes in ways that could make it far harder to later question how the guardianship was administered. Settling the accounting first keeps that scrutiny intact and independent of the adoption. A guardian who still owes an accounting, or who has unresolved obligations from mismanaging the ward's affairs, is not yet in a position to adopt under this rule.
The other requirements still apply, and adoption is no longer a court case
Meeting the guardian-specific condition does not excuse the general qualifications every adopter must meet: legal age, full civil capacity, good moral character, no conviction for a crime involving moral turpitude, emotional and psychological fitness to care for a child, and being at least sixteen years older than the ward, though that age gap can be waived in some situations. It is also worth knowing that the law setting out these qualifications, originally written as a court petition process, has been repealed and replaced by Republic Act No. 11642, which moved domestic adoption into an administrative process before the National Authority for Child Care rather than a case filed in court.