This study demonstrated the importance of identifying the optimal balance of hydrophilic and hydrophobic moieties in amphiphilic coatings to achieve fouling-release (FR) performance that surpasses that of traditional hydrophobic marine coatings. While there have been many reports on fouling-release properties of amphiphilic surfaces, the offered understanding is often limited. Hence, this work is focused on further understanding of the amphiphilic surfaces. Poly(ethylene glycol) (PEG) and polydimethylsiloxane (PDMS) were used to create a series of noncross-linked amphiphilic additives that were then added to a hydrophobic-designed siloxane-polyurethane (SiPU) FR system. After being characterized by ATR-FTIR, XPS, contact angle analysis, and AFM, the FR performance was evaluated by using different marine organisms. The assessments showed that the closer the hydrophilic and hydrophobic moieties in a system reached a relatively equalized level, the more desirable the FR performance of the coating system became. A balanced ratio of hydrophilicity-hydrophobicity in the system at around 10-15 wt % of each component had the best FR performance and was comparable to or better than commercial FR coatings.