The untied funds at sub-centers provided flexibility for local action at block and down below levels. Effective utilization of untied fund can strengthen the healthcare. So, our study aims at assessing the knowledge of health workers, male/female (HWF/M), and effectiveness of utilization of untied funds at the sub-center (SC) level. A mixed method (cross-sectional study and qualitative study) was conducted at Tangi Block, Khordha district, Odisha, in the year 2020. Health workers, male and female in sub-centers, and local stakeholders were interviewed using a structured interview schedule. The tool comprises financial records, a semi-structured questionnaire, and an in-depth interview guide. Universal sampling was adopted. For the cross-sectional study, 24 health workers were male/female, and for the qualitative study, all local stakeholders and 24 health workers female/male were interviewed. The study was conducted as a part of an academic program, and ethics approval was approved by AIIMS Bhubaneswar Institute Ethics Committee. Seven out of 24 sub-centers did not spend any money, with a median unspent amount of 4260 INR (Q1-0, Q3-17300). As many as 36.8% of sub-centers had a delay of 9 months to get the untied fund, which significantly affected the utilization of funds. 37% of HWF/M utilized the fund inappropriately. None of the health workers had complete knowledge regarding the appropriate usage of untied fund. Communication gap, multiple engagements, non-cooperation from officials, delay in technical processing, and irregular Garam Sabha meetings were found to be barriers. Our study found out under-utilization of money in untied fund. Communication gap, non-cooperation form village leaders, poor knowledge, overburdened health workers, improper reporting, and lack of felt need were found to be barriers for prompt utilization.