Construction over soft clayey soil is risky due to its low bearing capacity and high consolidation settlement. Underpinning or retrofitting of existing foundations using micropiles is a relatively modern and sophisticated method aimed at enhancing foundation strength, preventing movement, repairing or replacing existing foundations, and safeguarding against scour. In this study, locally accessible clayey soil from a paddy field near NIT Silchar was collected and a soft soil bed was prepared in a test tank in the laboratory. The aim of the study is to enhance the capacity of an existing shallow foundation rested on soft clayey soil using micropiles as a perimeter group. The size of the existing shallow foundation was considered to be 200 mm × 200 mm. A series of vertical load tests were conducted for different arrangement of perimeter micropile group such as vertical, inclined inward at 3°, inclined outwards at 3° and at reticulated (A-pattern) that is inclined inward and outward at 3° alternatively. Sixteen number of micropiles of diameter 20 mm and length 400 mm were arranged as a perimeter micropile group. The micropile cap size for enlarged group considered to be remained constant at 380 mm × 380 mm for all experiments. Load settlement graphs were plotted for all experiments. It is observed that ultimate load carrying capacity of enlarged foundation without micropile, with vertical micropile, micropile inclined inward, micropile inclined outward and A-pattern are 9.038 times, 10.76 times, 15 times, 13.84 times, 14.42 times more than the existing foundation, respectively. It can be concluded that the perimeter micropile groups inclined inward is most suitable in case of retrofitting in existing shallow foundation in soft clayey soil.