In this paper, we study scalar mediator induced nonstandard interactions (SNSIs) in the context of the ESSnuSB experiment. In particular, we study the capability of ESSnuSB to put bounds on the SNSI parameters and also study the impact of SNSIs in the measurement of the leptonic 𝐶⁢𝑃 phase 𝛿𝐶⁢𝑃. Existence of SNSIs modifies the neutrino mass matrix and this modification can be expressed in terms of three diagonal real parameters (𝜂𝑒⁢𝑒, 𝜂𝜇⁢𝜇, and 𝜂𝜏⁢𝜏) and three off-diagonal complex parameters (𝜂𝑒⁢𝜇, 𝜂𝑒⁢𝜏, and 𝜂𝜇⁢𝜏). Our study shows that the upper bounds on the parameters 𝜂𝜇⁢𝜇 and 𝜂𝜏⁢𝜏 depend upon how Δ⁢𝑚231 is minimized in the theory. However, this is not the case when one tries to measure the impact of SNSIs on 𝛿𝐶⁢𝑃. Further, we show that the 𝐶⁢𝑃 sensitivity of ESSnuSB can be completely lost for certain values of 𝜂𝑒⁢𝑒 and 𝜂𝜇⁢𝜏 for which the appearance channel probability becomes independent of 𝛿𝐶⁢𝑃.