Citizens Advice Scotland said the number of employment cases it had seen had risen by 12% in the last four years and was  now at its highest level.
It said the most common issues involved low pay, withheld wages and unfair dismissal, as well as bullying and discrimination.
CAS has highlighted the issues in a report to MSPs.
Holyrood's Economy, Energy and Tourism committee is exploring how employment and job quality has changed since the 2008 recession.
CAS said it had gathered evidence showing workplace problems were growing in Scotland.
Staff across its 61 sites reported that they were increasingly advising clients who were in work but struggling to pay for essentials.
Delivering the report to the Scottish Parliament, the charity's spokesman Rob Gowans said:  "What our report shows is the collected evidence of all the work-related cases that people have brought to the Scottish CAB (Citizen Advice Bureaux) service over the last few years.
"While we don't give away the identities of any of our clients, our evidence shows real-life experience. There is a growing crisis of low pay and poor conditions in Scotland.
"Around half of Scots who are in poverty are actually working. This reflects the fact that the minimum wage is not in fact keeping up with inflation, and many of the benefits that are meant to supplement low wages are being cut.
He added: "With wages falling in real terms, families are becoming trapped in poverty, less secure terms and working hours, and with basic employment rights becoming harder to enforce."
Mr Gowans also raised concerns about "too many rogue employers" who were "exploiting" workers under this environment.
"The growth in zero hours contracts has become a huge problem, which leaves thousands of Scots in huge financial uncertainty. And meanwhile it is becoming harder than ever to challenge unfair treatment," he added.
SNP MSP Christina McKelvie described the CAS report as "worrying" and called for the Scottish Parliament to be given more powers over employment policy.
She said: "This Citizens Advice Scotland report outlines the shocking impact of austerity, social security cuts and worrying examples of employers flouting employment law."
Scotland's workforce is "caught in a cruel trap" of low pay and poor conditions, according to a charity.