Later, Jones returned to Philadelphia, earned an M.D., and reopened his practice. Still, Jones never had much success as a doctor, and in 1832 he renounced medicine and headed for New Orleans, where he entered the mercantile trade. Once again, though, Jones's dreams were thwarted. Though he safely weathered two plagues, his business efforts never met with any success and within a year he was broke.
He was a member and Past Master of Harmony Lodge #52 of Philadelphia.
During the Texas Revolution, Jones served as a judge advocate and surgeon to the Texas army, though he insisted on holding the rank of private throughout the conflict. After the war, Jones returned to Brazoria and resumed his medical practice.
Upon his return to Brazoria, Jones found that James Collinsworth, a fellow Texas patriot (albeit one who did not serve in the army) and signer of the Texas Declaration of Independence from Brazoria, had set up a law practice in Jones's office. Jones evicted Collinsworth and challenged him to a duel (though the duel never occurred).
On March 1, 1835, Jones met with four other Masons at Brazoria and petitioned the Grand Master of Louisiana for a dispensation and a charter to form the first Masonic lodge in Texas. In December, when the lodge was set to labor, Jones was elected its first Master. The charter for Holland Lodge No. 36 arrived in April 1836, and Jones carried it in his saddlebags during the-Battle of San Jacinto. At the formation of the Grand Lodge of the Republic of Texas in December 1837, he was elected its first Grand Master.
Jones expected to return to his practice at Brazoria after his term in Congress, but Texas President Sam Houston instead appointed him Minister to the United States, where Jones was to formally withdraw the annexation proposal.
During this time, while many Texans hoped to encourage eventual annexation by the United States, there were some who supported waiting for annexation or even remaining independent. The United States, in the late 1830s, was hestitant to annex Texas for fear of provoking a war with Mexico. Jones and others felt it was important that Texas gain recognition from European states and begin to set up trade relations with them, to make annexation of Texas more attractive to the United States or, failing that, to give Texas the strength to remain independent.
Jones was recalled to Texas by new president Mirabeau Lamar in 1839. Back at home, he found himself elected to a partial term in the Senate, where he quickly became a critic of Lamar's administration. He retired from the Senate in 1841, declining the opportunity to serve as Vice President in favor of returning to his medical practice. However, late in 1841 he was named Texas Secretary of State by president Sam Houston, who had been recently been elected president again by opponents of Lamar.
Jones served as Secretary of State until 1844. During his term, the main goal of Texas foreign policy was to get either an offer of annexation from the United States, or a recognition of Texas independence from Mexico, or, preferably, both at the same time.
Finally, in June 1845, Jones's emissary to Mexico returned with a treaty recognizing the republic's independence. At last he put the question before the people — accept the offer of annexation from the United States, or sign the independence treaty from Mexico and remain an independent state. The Congress and the people went for annexation.
Preparations began for annexation, and Jones's role as president was greatly diminished. On February 19, 1846, a formal ceremony was held to bring Texas into the United States. Jones, in his last official act, declared that, "The Republic of Texas is no more." Then he retired to Brazoria.
Jones hoped that the new Texas state legislature would send him to the United States Senate. He was not chosen, and as time went on he became increasingly bitter about this slight. Although Jones prospered as a planter and eventually amassed an enormous estate, he was never able to get past the fact that Sam Houston was chosen over him to represent Texas in Washington, D.C.
In 1857, Jones became convinced that the legislature would finally send him to the Senate, but he received no votes. For four days he had lodged at Houston's Old Capitol Hotel, the former seat of government of the Republic of Texas, when he fatally shot himself in his room after dinner on January 9 1858. He was 59 years old.
Jones County, and its county seat, Anson, were both named for Anson Jones. His plantation home, known as Barrington, is preserved at Washington-on-the-Brazos State Historic Park.