Oncina is the principal designer at Manuel Oncina Architects, Inc., which he founded in 1984, to provide functional, sustainable, economical and exciting design, whether for public or private projects. The crux of the firm's practice is to apply simple and logical energy-efficient concepts while maintaining a keen aesthetic sense.

Oncina has 30 years of professional experience in design, construction documents, agency processing and construction support. He has received numerous awards for achievements in public and private design and engineering excellence. He is a member of the Society of American Registered Architects, the San Diego Foundation Arts & Culture Working Group and Lambda Alpha International.

His lifelong regard for fine arts is evidenced by his being an avid watercolorist and draftsman. Born in Casablanca, Morocco, Oncina was educated at the Université de Luminy, France; and in 1977 received a bachelor of science in architecture from California Polytechnic State University, San Luis Obispo.