A native Californian and beloved Southern California Chapter ASLA member, Troller was born and raised in Glendale. While studying landscape architecture at University of California, Berkeley he worked at the San Francisco offices of Eckbo, Royston and Williams, drafting and designing graphics. Royston convinced Troller to pursue an M.L.A., which he received in 1950.

Returning to Southern California, he worked briefly for Fred Barlow, Jr., before joining the office of Ralph Cornell as principal designer. Cornell made Troller and Bill Bridgers, who had joined the practice in 1953, partners in the firm Cornell, Bridgers and Troller in 1955. As Director of Design and Planning, Troller oversaw a growing staff of designers as the firm expanded outside Southern California to include national work with the Ford Motor Company in Detroit (1955), expanding internationally with the Nile Hilton in Cairo in 1959.

Projects of note designed by Troller include the University of California, Los Angeles' Franklin D. Murphy Sculpture Garden and Inverted Fountain; Grand Park, Los Angeles; and the Los Angeles City Hall East Mall. Troller left the firm in 1978, opening his own practice Howard E. Troller Associates, and later Troller Mayer Associates, Inc. with Richard Mayer.

Howard was elected Fellow of the American Society of Landscape Architects in 1992.