The Scottish government said the age limit was "outdated and ageist" and failed to recognise the extra life experience older people could offer.
The ban on over-65s serving as jurors had been in place since 1980.
But changes were made under the Criminal Justice and Licensing (Scotland) Act, which passed last year.
The Scottish government said the move would boost the pool of potential jurors available to Scotland's courts and ease the burden on younger members of the public who may have to juggle family and work commitments.Valuable contribution
Under the new arrangements those aged 71 and over who do not want - or feel able - to serve on a jury will have the right to be excused.
Justice Secretary Kenny MacAskill said: "Scotland's jury service system was outdated, ageist and in need of modernisation.
"Scots continue to live active lives long after retirement and they make a valuable contribution to communities up and down the country.
"The idea that they should be debarred from taking part in jury duty was frankly ridiculous, insulting and it is time for change."
Mr MacAskill said juries should be a true reflection of society.
Currently those attending court for jury service have a right to be excused for five years, whether they serve or not.
Under the new law, those who attend but are not selected only have a right to be excused for two years.
Each year 150,000 people are called for jury service of which about 10% are selected.