As a child, Henry Jr. moved with his family to St. Louis, Missouri, during the early period of the Great Migration of African Americans from the rural South to industrial cities of the Midwest and North.

He graduated as an honor student from Vashon High School in St. Louis[10] Later he took the surname Armstrong as his fighting name.

In 1932, Armstrong moved to Los Angeles, where he lost two four-round decisions in a row to Eddie Trujillo and Al Greenfield.

A few notable opponents of that year include Ritchie Fontaine, Baby Arizmendi, former world champion Juan Zurita, and Mike Belloise.

[14] In 1938, Armstrong started his season with seven more knockouts in a row, including one over Chalky Wright, a future world champion.

The streak finally ended when Arizmendi lasted ten rounds before losing a decision to Armstrong in their fourth fight.

[13] Armstrong dedicated the next two years to defending the welterweight crown, beating, among others, Ceferino Garcia, a future World Middleweight Champion, and Bobby Pacho.

He defended it in eight fights in a row, the last of which was a nine-round knockout win over Puerto Rico's Pedro Montañez.

[11] After retiring from boxing in 1946, Armstrong briefly opened a Harlem nightclub, the Melody Room (named after his first nickname).

[17] He returned to settle again in St. Louis, Missouri where, apart from the ceremonies and galas that he attended afterward, he led a quiet retirement.

He became a born-again Christian and an ordained Baptist minister and youth advocate, helping to run the Herbert Hoover Boys Club.