Vincent Friel crashed into Charlotte Collins, 68, and her cousin Margaret Haldane, 69, near Silverburn shopping centre in Glasgow on 18 January 2014.
Ms Collins died shortly afterwards and Ms Haldane was seriously injured.
Friel, 44, from Rutherglen, South Lanarkshire, was also banned from driving for five years.
Jailing Friel at the High Court in Glasgow, judge John Morris QC told him: "You were a normal respectable member of the community until the date of this accident.
"I take into account the exceptionally slow speed your vehicle was travelling at. However, you drove through a pedestrian crossing on a red light causing the death of one lady and injuring another.
"Miss Collins relatives have lost a much loved family member. The effect on the families has been devastating. No sentence I can pass will assuage such devastation. No sentence passed by a judge will ever be viewed by the families as adequate."
The court previously heard that Friel's Range Rover ploughed into the women at a pedestrian crossing in Barrhead Road.
Friel, who owns a property letting business employing 20 people, was taking blood pressure medication at the time of the collision.
He had also been prescribed Viagra and medicine to take away headaches that were brought on by having sex.
His lawyers claimed the combined medicine caused his blood pressure to drop to such a low level as to cause him to faint and he was not in control of his actions at the time.
The court heard from one doctor, described as a world-renowned expert in his field, who said it was "likely or possible" that Friel had suffered a "vasovagal" episode, another term for a faint.
However, cardiologist Dr Andrew Flapan told jurors he thought it was "extremely unlikely" that Friel had fainted at the wheel of his 4x4.
He pointed to the fact Friel looked normal after the crash and was able to reverse his car off one of the women and use his mobile phone to call for an ambulance, saying he would not be able to do these things for at least 20 minutes after fainting.
A jury of nine women and six men took just one hour and 40 minutes to find Friel guilty of causing the death of Ms Collins and the serious injury of Miss Haldane by driving dangerously.

The 2014 Commonwealth Games silver medallist improved her English record to 65.10 metres at the New South Wales Championships in Sydney.
It puts her second in the all-time British list behind Scotland's Margaret Ritchie, who threw 67.48.
It is the second time she has thrown an Olympic qualifying mark in three days.
The 28-year-old threw 64.22m at the Auckland Track Challenge on Thursday.

Darrell Clarke's side clinched third in League Two with a last-gasp winner on Saturday against Dagenham & Redbridge.
New Zealand forward Rory Fallon, 34, is to be released after making just three first-team appearances this season.
Defenders Lee Brown, scorer of the late winner over Dagenham, and Tom Lockyer already signed new contracts in April.
Having secured back-to-back promotions, securing top scorer Matty Taylor's services for at least another season would be seen as a major boost for the club if he was to agree a new deal.
After Saturday's victory, the striker told BBC Radio Bristol he would speak to club's president regarding a new deal.
Chairman Steve Hamer has said the club will have the chance to match offers made by other clubs for Taylor this summer.
A man who was convicted of causing death by dangerous driving after jurors rejected claims that he fainted at the wheel has been jailed for three years.
[NEXT_CONCEPT]
Jade Lally has produced the longest discus throw by a British woman since 1983 to move to fourth in the 2016 world rankings.
[NEXT_CONCEPT]
Promoted Bristol Rovers have offered new contracts to all but one of their senior professional players after their dramatic finish to the league season.