In the wake of the 1989 Loma Prieta earthquake and the 1994 Northridge earthquake he was a member of various California Department of Transportation (Caltrans) committees and commissions reviewing the design of damaged bridges, and was also a member or chair of a number of Caltrans committees investigating the seismic strengthening of existing structures.

[6][8] Priestley was author or co-author of over 450 scientific papers and 250 research reports, and was the primary advisor for more than 25 doctoral students.

His three books are regarded as canonical texts in their particular areas:[6] His research at UCSD with Frieder Seible following the 1989 Loma Prieta earthquake into structural deficiencies in reinforced concrete columns supported bridges in California led to the development of an economical retrofit solution involving the installation of a metal jacket to reduce the risk of column failure in seismic events.

[10][11] A team led by Priestley developed PRESSS (precast seismic structural system), a design methodology for earthquake-resistant buildings in which the building is designed as a collection of rocking blocks able to move independently of each other during a seismic event but are pulled back into their original position by unbonded post-tensioning cables within the precast concrete structure.

[5] In the 2014 Queen's Birthday Honours, Priestley was appointed an Officer of the New Zealand Order of Merit, for services to structural engineering.