Background: To evaluate the role of ultrasound during initial fluid resuscitation along with clinical guidance in reducing the incidence of fluid overload on day 3 in children with septic shock. Materials and methods: It was a prospective, parallel limb open-labeled randomized controlled superiority trial done in the PICU of a government-aided tertiary care hospital in Eastern India. Patient enrolment took place between June 2021 and March 2022. Fifty-six children aged between 1 month and 12 years, with proven or suspected septic shock, were randomized to receive either ultrasound-guided or clinically guided fluid boluses (1:1 ratio) and subsequently followed up for various outcomes. The primary outcome was frequency of fluid overload on day 3 of admission. The treatment group received ultrasound-guided fluid boluses along with the clinical guidance and the control group received the same but without ultrasound guidance upto 60 mL/kg of fluid boluses. Results: The frequency of fluid overload on day 3 of admission was significantly lower in the ultrasound group (25% vs 62%, p = 0.012) as was the median (IQR) cumulative fluid balance percentage on day 3 [6.5 (3.3–10.3) vs 11.3 (5.4–17.5), p = 0.02]. The amount of fluid bolus administered was also significantly lower by ultrasound [median 40 (30–50) vs 50 (40–80) mL/kg, p = 0.003]. Resuscitation time was shorter in the ultrasound group (13.4 ± 5.6 vs 20.5 ± 8 h, p = 0.002). Conclusion: Ultrasound-guided fluid boluses were found to be significantly better than clinically guided therapy, in preventing fluid overload and its associated complications in children with septic shock. These factors make ultrasound a potentially useful tool for resuscitation of children with septic shock in the PICU.