In the 21st Century, businesses have maximized the opportunities of media advertising to communicate their products and services to customers. As time progressed, advertising firms preferred applying traditional strategies to clients' advertisements, such as celebrity endorsements, telemarketing, and print media. Small and medium-sized enterprises, or SMEs, have a significant role in most economies. With these businesses having several employees below a certain threshold and a limited budget, some SMEs set themselves apart from competitors by using unique and creative strategies commonly called Guerrilla Marketing. Through a mixed-method approach, the researchers determined the effects of Guerrilla Marketing on Small and Medium-sized Enterprises in Metro Manila. The researchers deployed questionnaires to 385 respondents and an online interview with 13 employees. The results of this study shall contribute to the body of knowledge of businesses, more particularly SMEs, on whether it is beneficial for them to adopt such marketing strategies.