The two-time Grand Slam champion made undisclosed investments through the crowdfunding firm Seedrs.
Crowdfunding is a means of raising cash through lots of small investments from a large number of people, not necessarily professional investors. Seedrs has a £10 minimum investment.
The tennis star's investments are with desserts business Oppo Ice Cream, online transport advice site CommuterClub, peer-to-peer mortgage lender Landbay, film streaming firm We Are Colony, and magazine subscription app Readbug.
Murray said: "Giving recognition and support to British entrepreneurs is important to me, especially those who are the driving force behind growth-focused businesses.
"Every one of these entrepreneurs is inspirational and dedicated to their business and I'm excited to have invested in their team's vision and work ethic."
The sportsman joined the Seedrs advisory board in June and made investments of undisclosed amounts with three young firms then.
The crowdfunding business said he plans to make further investments later this year.
Seedrs, founded in 2012, said its platform has raised more than £100m for investment in young businesses, covering more than 320 deals, and on average raises up to £7m per month.
Murray is the reigning Olympic champion in singles, and won the US Open title in 2012 and Wimbledon a year later.
Last year he lead Great Britain to its first Davis Cup win in 79 years, and will lead the team in their defence of the trophy against Japan on 4 March.
Earlier this month his wife gave birth to their first child.