High salt concentration and salinity fluctuations in wastewater challenge the efficiency of microbial strains used for cleanup of pollutants. In this study, it was investigated that the new isolated Arthrobacter sp. W1 degraded mixed phenolic compounds under complex salt conditions. The results showed that Arthrobacter sp. W1 was able to utilize various phenolic compounds as carbon source under high salt conditions. It can degrade phenol and p-cresol mixture at 10% NaCl, although rates of degradation and cell growth were lower compared to 5% NaCl. The presence of trace p-cresol significantly inhibited phenol biodegradation. When salinity fluctuations were between 1% and 10% NaCl, strain W1 was able to degrade substrates and survived. It was also suggested that the presence of salts (i.e., NaCl, KCl, Na2SO4, and K2SO4) had almost no effects on the microbial growth and biodegradation process. Therefore, Arthrobacter sp. W1 would be a promising candidate for bioremediation of phenolic compounds under complex salt conditions.