Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer lacks estrogen, progesterone, and HER2 receptors and hence, is therapeutically challenging. Towards this, we studied an alternate therapy by repurposing metformin (FDA-approved type-2 diabetic drug with anticancer properties) in a 3D-scaffold culture, with electrical pulses. 3D cell culture was used to simulate the tumor microenvironment more closely and MDA-MB-231, human TNBC cells, treated with both 5mM metformin (Met) and 8 electrical pulses at 2500V/cm, 10µs (EP1) and 800V/cm, 100µs (EP2) at 1Hz were studied in 3D and 2D. They were characterized using cell viability, reactive oxygen species (ROS), glucose uptake, and lactate production assays at 24h. Cell viability, as low as 20% was obtained with EP1+5mM Met. They exhibited 1.65-fold lower cell viability than 2D with EP1+5mM Met. ROS levels indicated a 2-fold increase in oxidative stress for EP1+5mM Met, while the glucose uptake was limited to only 9%. No significant change in the lactate production indicated glycolytic arrest and a non-conducive environment for MDA-MB-231 growth. Our results indicate that 3D cell culture, with a more realistic tumor environment that enhances cell death using metformin and electrical pulses could be a promising approach for TNBC therapeutic intervention studies.