Twigg-Smith grew up in the lower Nu'uanu area on Bates Street, in a house his father built on his Grandfather Lorrin's property. At the time, L.A. Thurston was publisher of The Advertiser.

Twigg-Smith, his brother David and sister Barbara attended Lincoln and Kapalama elementary schools. Twigg-Smith went on to Roosevelt for junior high and entered Punahou in the 10th grade on a scholarship.

Twigg-Smith won a scholarship to Yale and graduated in 1942 as a mechanical engineer. Today he contributes substantially to both schools.

He served in five campaigns in Europe in World War II. He attained the rank of captain in the field artillery and was awarded the Bronze Star. Returning to Hawai'i in December, 1945, he started work at The Advertiser in February, 1946 and as a major, started the 483rd Field Artillery battalion in the Hawai'i National Guard. He left the guard in 1954 as a lieutenant colonel to concentrate on his then duties as managing editor of the newspaper.

His uncle, Lorrin P. Thurston, was publishing The Honolulu Advertiser. The paper was in serious financial difficulties when Twigg-Smith went to work there. He worked in all departments, including ten years in the editorial department.

Twigg-Smith's side of the family controlled some of the Advertiser stock and he banded with others in the community to take control of the newspaper in December 1960. He was publisher of the paper from early 1961 until 1993, when the now-financially sound and profitable paper was sold to Gannett.

Twigg-Smith has been a major supporter of non-profit service organizations and of the arts, and in 1997 was named Hawai'i's Philanthropist of the Year.

He began researching the book, Hawaiian Sovereignty: Do the Facts Matter? in 1994, the year after the 100th anniversary of the Revolution because he believes fiction and revisionism are replacing facts in Hawai'i history.