Miyagishima won re-election as to the city council in 2005. Miyagishima is the first American of Japanese and Mexican descent to be elected mayor of Las Cruces. He is also the second person in Doña Ana County to have been elected both chairman of the Doña Ana County Commission and mayor of Las Cruces.
In 2019, Miyagishima was re-elected to his fourth term as mayor of Las Cruces.
Ken and Rosie have four children. Danielle is attending Yale Medical School, while John and Frank are both attending NMSU studying engineering. Carlos is a junior at Centennial High School.