Bush, who worked in finance, was the last surviving of the family's five siblings.
George H.W. Bush died in 2018 at his Houston home. Their sister, Nancy Bush Ellis, died in January. Brother William Henry Trotter Bush, known as "Bucky," died in 2018, and brother Prescott S. Bush Jr. died in 2010.
Their father was Prescott Sheldon Bush, a U.S. senator from Connecticut from 1952 to 1963.
Jonathan Bush helped raise funds for his nephew's presidential campaign and was among family members his brother sent to be official stand-ins at ceremonies across the world.
Jonathan Bush was the father of Billy Bush, who was fired by NBC due to the infamous "Access Hollywood" tape with Donald Trump and now hosts the pop culture news show "Extra." In an Instagram post, Billy Bush called his father "the greatest man I'll ever know."