Official figures show 27,547 marriages were registered last year, nearly 3,000 down on the previous year and reversing a trend after three consecutive increases.
The latest figure is only 23 higher than the low point recorded in 2009, according to the National Records of Scotland (NRS).
Fewer people were also born or died in 2013.
Registered births decreased from 58,027 to 56,014.
Deaths dropped from 54,937 to 54,700, which is the fourth lowest number recorded in more than 150 years.
There were 530 civil partnerships, down 44 on the previous year.
Tim Ellis, chief executive of the NRS, said: "The number of births fell in 2013, continuing the trend of gradual decline from the most recent peak of 60,041 in 2008.
"Levels of births and deaths are both relatively low in historical terms and there have been more births than deaths each year since 2006.
"In recent years, the annual number of deaths has been below 55,000, compared to levels of around 60,000 to 65,000 from the mid-1940s to the mid-1990s, and larger numbers before then."