Short answer. Yes. If you have habitually and continuously used a name and are publicly known by it in your community, that is a recognised ground to make it your registered first name. You may petition the local civil registrar for the change without a court case, provided you can show the long, public use.
What the law says
The new first name or nickname has been habitually and continuously used by the petitioner
RA 9048, Section 4 — Grounds For Changing First Name. Read the full provision →
Long public use is a recognised ground
Republic Act No. 9048 lists the grounds for changing a first name, and yours is the second of them. Section 4 allows the change where the new first name or nickname has been habitually and continuously used by the petitioner and he has been publicly known by that name in the community. This is the classic situation of a person whose birth certificate says one thing while everyone — family, neighbours, schoolmates, employers — has called them something else for years. The law recognises that a name lived under, openly and consistently, has a reality of its own, and it lets you bring your record into line with the name you are actually known by.
Habitual, continuous, and public
The ground has three linked ideas, and all matter. The use must be habitual and continuous — an established, unbroken practice, not an occasional or recent nickname — and you must be publicly known by the name in your community, so that it is your identity to the people and institutions around you. A pet name used only at home, or a handle you picked up last year, will not carry the same weight. The stronger your history of being known by the name in everyday life and in your dealings, the better the ground fits, because that public, settled usage is exactly what the provision is testing for.
Filed with the civil registrar, first name only
Like the other grounds under RA 9048, this is decided administratively rather than in court. You file with the city or municipal civil registrar keeping your birth record, or the consul if you are abroad, and the registrar rules on the petition under the Act. The change covers your first name or nickname, not your surname, so this is the route for making the nickname your official given name — not for altering your family name. You will identify the name you have been using and are asking to adopt, and the registrar assesses whether the long public use the ground requires is genuinely there.
What can stand in the way
The registrar has to be satisfied that the use is real and public, so a thin or purely private claim can fall short. Being known by the name to a wide circle over a stretch of years is persuasive; being called it only now and then is not. The Act also requires notice so the change is transparent, and it reaches the first name alone — if what you actually need touches a surname or a substantial entry, that is a different matter outside this ground. If the petition is refused, or if your case goes beyond the administrative route, a judicial remedy is still available. Getting advice helps you present the public-use history convincingly.