Short answer. Very likely yes. Under the Labor Code, employment is regular where the work is usually necessary or desirable in the employer's business, whatever the contract says. Three years of the same duties is strong evidence of exactly that, unless the work was genuinely a project or seasonal.
What the law says
an employment shall be deemed to be regular where the employee has been engaged to perform activities which are usually necessary or desirable in the usual business or trade of the employer
Labor Code, Article 280 — Regular And Casual Employment. Read the full provision →
The test looks at the work, not the label
The article turns on one question: are the activities you perform usually necessary or desirable in the employer's line of business? A cashier in a store, a machine operator in a factory, a nurse in a hospital — these are the business itself, not something incidental to it. Doing the same duties for three consecutive years is about as clear a demonstration of necessity as the facts can give, since an employer does not renew a role that often unless the role is part of how it operates.
The two exceptions, and why they rarely fit
Regular status yields in two situations. The first is work fixed for a specific project or undertaking the completion or termination of which has been determined at the time of the engagement — note the timing: the endpoint must have been identified when you were hired, not decided later. The second is work seasonal in nature, engaged for the duration of the season. Repeatedly renewing short contracts for continuing work is neither. A series of five-month engagements on the same job is not a project.
The one-year provision is a second, independent route
Even if your work were only casual, the article adds that any employee who has rendered at least one year of service, whether such service is continuous or broken, shall be considered a regular employee with respect to the activity in which he is employed. So a worker outside the first paragraph still becomes regular after a year in that activity, and gaps between engagements do not reset the count. At three years, both routes point the same way.
What proves the years
Collect every contract you signed, your payslips, identification cards, schedules, and anything showing the duties you actually performed and the dates you performed them. Continuity is what the employer will contest, so records covering the gaps between contracts matter most. Note also that regular status is about security of tenure, not automatically about a change in pay — the practical consequence is that ending your employment then requires a just or authorised cause and the proper procedure.