Peter Bottomley, from Morecambe, was an authorised Independent Financial Advisor until 2003.
Preston Crown Court heard that, despite his authorisation to be an IFA ceasing, he continued to manage the finances of some elderly people who later went on to reside in local care homes, often with no next of kin. The total amount he took was £356,883.16.
The investigation started with a victim with cerebral palsy, from whom he stole £103,646.48. The investigation then revealed Peter Bottomley had tricked a number of other people in the same way and created wills which would have been to his benefit.
Elizabeth Jenkins, deputy head of the Specialist Fraud Division at the CPS, said: "To steal money from anyone is unacceptable, but to steal the life savings of the vulnerable and the elderly is particularly cruel and calculating.
"The strength of our evidence was such that Peter Bottomley had no choice but to plead guilty which spared the victims from a potentially lengthy trial.
"It was clear that Peter Bottomley selected his victims because he thought their age, and in one case their cerebral palsy, made them easy targets. We asked the court to reflect the pernicious way in which he targeted these vulnerable victims in its sentencing.
"Crimes like this should not pay and we have already succeeded in restraining £1.3m worth of Peter Bottomley's assets. We'll now continue to work hard to ensure this money is recovered and his victims are compensated."