Robert Palmer, 32, mowed down Andrew McMenigall, 47, and Toby Wallace, 36, who died almost instantly in the crash on the A30 in Newquay, Cornwall, on 2 July last year.
The pair, who were colleagues working for Aberdeen Asset Management, were just 40 miles into the 960-mile bike ride to raise money for two charities when they were struck by the white Renault lorry driven by Palmer.
At an earlier hearing at Truro Crown Court, Palmer, of Cornwall, pleaded guilty to two charges of causing death by dangerous driving.
He also admitted a further charge of dangerous driving in relation to a second similar crash weeks later on the A30 near Okehampton.
At the time of the crash Palmer, a night-time delivery driver, had little sleep because instead of resting during the day he was working on vehicle maintenance for the firm.
He was also habitually using his iPhone to send text messages while carrying out deliveries for discount store Lidl, the court heard.
Jailing the father-of-one, Judge Christopher Harvey Clark QC said: “The evidence is, at the time when this accident occurred you had almost certainly fallen asleep but it is equally clear you were disregarding the rules of the road by texting continuously and it would seem at length.
“You completely ignored their presence on the road. In the words of prosecutor Mr Lee you mowed them down.
“It is clear that at the time when this tragic accident occurred you were suffering from extreme fatigue and exhaustion.”
Palmer was also banned from driving for ten years and ordered to take an extended driving test.
The judge said both Mr McMenigall and Mr Wallace were very successful in both their careers and personal lives.
“Both men were experienced and safe cyclists. It is clear at the relevant time they were visible to other road users,” the judge told Palmer.
“They met their deaths as a result of your criminal actions. I recognise the terrible loss to their families and friends. They cannot be replaced.”
Mr McMenigall lived in Edinburgh with his wife Anne and their two children, Jennifer, aged 15, and 12-year-old Lucy.
He was a keen triathlete and had previously served as an officer in the army before joining AAM.
Mr Wallace, who was married to Claire, lived in Philadelphia where he worked for AAM.
In a joint statement Anne McMenigall and Claire Wallace, the widows of the cyclists, said: “There are no words to describe the devastation and loss that we feel, and both families feel, following the deaths of our husbands. They were exceptional and giant men in every sense of the word.
“It is a tragedy so many other families are also mourning loved ones who have been killed on Britain’s roads, particularly when many of these deaths were completely avoidable.
“UK transport laws are lenient, charges are difficult and onerous to attain, and less and less resource is being dedicated to road traffic collisions.