Lewis Rodden, from Cumbernauld, and three members of his security firm admitted assault, possessing offensive weapons, threats and fire-raising.
The 44-year-old ringleader was jailed alongside Muir MacLeod, 38, Lee Burgun, 34, and William Bennett, 45, at the High Court in Kilmarnock on Friday.
The judge likened the crime spree to mobster racketeering in 1920s America.
A fifth man, James McInally, 47, was put on probation for three years and ordered to carry out 240 hours' community service.
Mob mentality
Rodden was in charge of the four men who all worked for his private security outfit, West Coast Security.
Last month the same court heard he and his accomplices plead guilty to a series of charges related to trying to bully construction firms across Ayrshire into awarding them business between May and September 2003.
On sentencing the quartet on Friday, Lord Hardie said: "Such crimes remind me of the activities of organised crime in America last century."
He added that the acts of violence against rival security firms in order to obtain their business was unacceptable and welcomed the introduction of licences to stop such activities by the Scottish Executive.
Lord Hardie jailed Rodden, MacLeod, from Maybole, for five years, Burgun, also from Maybole, for four years and Bennett, from Glasgow, for four years.
Friends and family of the accused wept as they were led away to the cells.
Armed guards
At the court last month all the men admitted threatening and assaulting Gordon Wylie, an employee of Guardwise Security, on a construction site in Ardrossan in September 2003.
Rodden admitted possessing a samurai sword on the day of the attack while MacLeod pleaded guilty to possessing a baseball bat, two hammers and a wrench.
MacLeod and Burgun also admitted setting fire to a portable toilet at another building site in East Ayrshire in May of the same year. They struck after the site owner, George Pattison, of GS Homes, refused to award them work to guard the premises.
The pair also confessed to removing signs belonging to another rival, Castle Security, from a building site in Ayr in August after telling its staff that West Coast Security was taking over.
They had earlier intimidated the firm's owners, Thomas and Elizabeth Easdon, of Irvine, by demanding they surrender the contract at the site.