Haney was born on August 22, 1952 and raised in rural Lindale, Georgia, just outside of the town of Rome. He attended Pepperell High School there, graduating in 1970.

Haney joined the Army just out of high school in 1970 and became a platoon sergeant by the time he was 22. He served for several years in the 75th Ranger Regiment as an infantryman and was slated to become an instructor. In 1977 he volunteered for and was selected to train with a new elite counter-terrorism unit that the Army was creating. Of the 163 soldiers that tried out, Haney was one of only 12 to succeed. This unit became operational in 1978 as the 1st SFOD-D, or Delta Force, with Haney joining the unit at least 13 months later and after training and operational acceptance nearly six months after that he became a full member of the unit. The unit had been formed and organized by Col Beckwith approximately 19 months before Haney became an asset and operator with the unit. Haney served in the unit until 1986, participating in a number of special operations in Latin America and the Middle East.

After his promotion to Command Sergeant Major, the rank he held until his retirement in 1990, Haney left Delta and joined the 193rd Infantry Brigade (Panama).

Operation Eagle Claw

In 1980, when the United States launched Operation Eagle Claw, an attempt to end the Iran hostage crisis with a commando raid, Haney was one of the Delta operators to take part. He was inside the parked C-130 tanker/transport aircraft that caught fire and exploded when a Navy RH-53D helicopter piloted by Marine aircrews collided into it after the mission had been aborted and the unit was preparing to exfiltrate. After the debacle he and other Delta operators were told to "take a vacation" in order to avoid any media scrutiny.

Honduras

In 1981, Haney and two Delta Force operators were deployed to Honduras to train Honduran Special Forces when they were sent on a mission to intercept and destroy a group of Honduran communist guerrillas that had infiltrated the country from Nicaragua. This group of around 100 rebels was allegedly being led by an advisor in the Nicaraguan Sandinista Army.

Haney states that his team, composed of the Delta operators and Honduran special forces soldiers, tracked the guerrillas to a mountain sanctuary in the Honduran jungle. During an assault on the hilltop, Haney spotted a guerrilla using a radio set and taking him for the leader, shot and killed him. Haney soon discovered that this commander turned out to be David Arturo Báez, a Nicaraguan-born U.S. citizen and former Army Special Forces soldier whom Haney had met during his Delta selection.

In his memoir, Haney questioned whether Báez had actually joined the Sandinistas or whether Báez was still working for the United States as a CIA operative up until his death. (Báez is referred to in Haney's book as "Enrique 'Keekee' Sáenz.")

Several former Delta members who were also with Delta at the time of this alleged incident, to include his Squadron Commander, have disputed this entire incident and have stated it is a complete fabrication. An interview published in the Miami Herald relates that Baez's family had heard accounts of his death which resemble the version that Haney describes in his book.

Beirut

During the 1982 Marines operation in Lebanon, Haney was deployed with other Delta Force members to train local Lebanese as part of the U.S. Embassy security detail. Later, he and his teammates were tasked with locating and eliminating snipers who were targeting Marines deployed there as part of a United Nations peacekeeping mission.

Grenada

In 1983, the U.S. invasion of Grenada in Operation Urgent Fury. Haney and other Delta operators were assigned to raid a prison thought to hold political prisoners. Their helicopters came under heavy enemy fire, and they determined that the prison was empty. The raid was called off.

the publication of Inside Delta Force in 2002 and Haney's subsequent success with The Unit television show, three of his former Delta colleagues accused him of embellishing his accomplishments within the unit and fabricating several of the events depicted. Some of the criticism directed at Haney has focused on him stating he was a "founding member" of Delta Force; it's acknowledged among former operators that there was only one "founder", Colonel Charlie Beckwith, who helped establish the unit and was its first commanding officer.

One such colleague, Logan Fitch, who first wrote publicly of the Desert One mission for Penthouse Magazine in 1984 in which he was also highly critical of Beckwith, called Haney a "crass opportunist" for capitalizing on his past for personal gain. Despite the falling-out between Haney and these former Delta members, Haney has stood behind the accuracy of his book.

Another member criticized Haney for revealing too much about Delta Force's training, tactics and early missions. A U.S. Army historian has questioned whether this was an issue, given that the information contained in Haney's book was current during the late-1970s and early-1980s and that Delta Force would certainly have changed their procedures since then. Moreover, operational information offered by Delta veterans had been made public before, for instance in Black Hawk Down, Mark Bowden's book about the Battle of Mogadishu, and most notably in Delta Force: The Army's Elite Counterterrorist Unit, Beckwith's own account about the formation and training of the unit.

Upon retiring from the Army in 1990, Haney was employed as a freelance security consultant and trainer. He worked within the United States and abroad as a bodyguard, trainer for military and police forces, and private kidnap rescuer.

Some of Haney's assignments in the private sector include conducting the ransom negotiation and ransom hand-over for a kidnapped oil executive in Colombia, and helping governments in two Middle Eastern countries develop their special forces capabilities. He also worked for several years as personal security detail leader for several high-profile clients, such as Saudi Prince Khalid al Faisal, the CEO of the largest corporation in Mexico, and Haitian President Jean-Bertrand Aristide upon his return from exile in 1994.

During the 1990s, Haney performed security consulting work in Algeria on a gas pipeline project, and started a contract aviation company in Liberia. Some time after that, Haney was approached about organizing and leading a coup attempt in another African nation. He was able to completely thwart the parties who wanted that coup, several of the conspirators were arrested a short while later.

After the September 11, 2001 terrorist attacks, Haney became a regular television commentator on military affairs and terrorism, appearing on CNN, Fox News, CBS News and The O'Reilly Factor. Recently he has expressed opinions strongly critical of the planning and implementation of Operation Iraqi Freedom

Haney was the host of a television series entitled "Spymaster USA," which aired on The Learning Channel in 2004.

Haney was involved as a writer, producer, and technical advisor for the CBS television series The Unit, loosely based on his book.