<p>This study investigated the oxidative stability and growth-promoting effect for <i>Lactobacillus acidophilus</i> ATCC 43121 of a nanoemulsion delivery system (NDS) composed of whey protein isolate (WPI)/inulin Maillard conjugates. WPI/inulin Maillard conjugates prepared at pH 8.4 and a temperature of 85&#xa0;°C had enhanced ABTS radical scavenging activity and were used as coating materials for the NDS. The WPI/inulin Maillard conjugates-based NDS exhibited a smaller droplet size than the WPI-based NDS. A droplet size of approximately 180&#xa0;nm was observed in the NDS containing the WPI/inulin Maillard conjugates. The WPI/inulin Maillard conjugates-based NDS maintained a consistent droplet size and polydispersity index throughout 16 d of storage, indicating excellent physical stability. Compared to both fish oil encapsulated in NDS and WPI-based NDS, fish oil in WPI/inulin Maillard conjugates-based NDS demonstrated lower PV and <i>p</i>-anisidine value and reduced production of potential markers of oxidation during a 16 d storage period. This indicated that the WPI/inulin Maillard conjugates-based NDS had enhanced oxidative stability. The viability of <i>L. acidophilus</i> ATCC 43121 increased in minimum media supplemented with WPI/inulin Maillard conjugates-based NDS compared to WPI- or inulin-based NDS, suggesting that WPI/inulin Maillard conjugates-based NDS had a growth-promoting effect for <i>L. acidophilus</i> ATCC 43121. In conclusion, the use of WPI/inulin Maillard conjugates-based NDS is an effective way to enhance the oxidative stability of fish oil and its growth-promoting effect for <i>L. acidophilus</i> ATCC 43121.</p>