In comparison, they have invested a net amount of Rs 9,244 crore in the stock markets.
Moreover, mutual fund houses are upbeat about overall inflows in equities and debt markets for the current financial year (2015-16) as well.
Industry experts have attributed the inflows in debt markets during 2014-15 to the new government's reforms agenda, improved fundamentals of the domestic economy and increased participation from retail investors.
"Improved sentiments and the reforms initiative taken by the the Central government has helped in the inflow," Axis Mutual Fund Managing Director and CEO Chandresh Nigam said.
As per data released by the Securities and Exchange Board of India, mutual fund managers invested a net sum of Rs 22,650 crore in the debt markets in April.
Besides, fund managers invested a net amount of nearly Rs 6 lakh crore in debt markets in the last financial year, 2014-15.
This inflow has helped in raising the assets base of mutual fund industry to Rs 11.86 lakh crore mark at the end of last month from Rs 10.83 lakh crore at the March-end.
In comparison, Foreign Portfolio Investors (FPIs) made a net investment of Rs 3,612 crore into debt markets in April.
A mutual fund is an investment vehicle with a pool of funds collected from investors to buy securities such as stocks, bonds and money market instruments.