diff --git a/src/handlers/kboHandlers.ts b/src/handlers/kboHandlers.ts
index b7f2a86..d787c24 100644
--- a/src/handlers/kboHandlers.ts
+++ b/src/handlers/kboHandlers.ts
@@ -5,6 +5,7 @@ import { getPlayerStats, getValidPlayerTypes } from "../services/playerService";
 import { getGameList } from "../services/gameListService";
 import { getGameDetail } from "../services/gameDetailService";
 import { TeamCode } from "../types/panit";
+import { kboTodayKst } from "../types/dateString";
 
 enum KboPath {
   Rank = "rank",
@@ -60,9 +61,12 @@ export const kbo = onRequest(async (req, res) => {
       const year = parseIntParam(req.query.year, now.getFullYear());
       const month = parseIntParam(req.query.month, now.getMonth() + 1);
       const series = req.query.series ? String(req.query.series) : undefined;
-      const day = req.query.day !== undefined
-        ? parseIntParam(req.query.day, NaN)
-        : undefined;
+      const dayRaw = req.query.day;
+      const day = dayRaw === undefined ?
+        undefined :
+        String(dayRaw) === "today" ?
+          parseInt(kboTodayKst().slice(8, 10), 10) :
+          parseIntParam(dayRaw, NaN);
 
       if (year < 1982 || year > 2100) {
         res.status(400).json({ error: `Invalid year: ${year} (1982~2100)` });
diff --git a/src/types/dateString.ts b/src/types/dateString.ts
index 7147ab5..ce9ab71 100644
--- a/src/types/dateString.ts
+++ b/src/types/dateString.ts
@@ -38,6 +38,18 @@ export function todayKst(): DateString {
   return toDateString(new Date());
 }
 
+/** KBO 데이터 기준일의 컷오프 시각(KST). 일일 갱신(02:00) 직후 버퍼 1시간. */
+const KBO_DAY_CUTOFF_HOUR = 3;
+
+/**
+ * KBO 데이터 기준의 "오늘". 일일 갱신 잡이 02:00(KST)에 돌기 때문에
+ * 새벽 03:00 이전에는 당일 데이터가 아직 확정되지 않아 직전일을 반환한다.
+ * `now`는 테스트 주입용(기본 현재 시각).
+ */
+export function kboTodayKst(now: Date = new Date()): DateString {
+  return toDateString(new Date(now.getTime() - KBO_DAY_CUTOFF_HOUR * 60 * 60 * 1000));
+}
+
 /** n일 전 KST 날짜. */
 export function daysAgoKst(n: number): DateString {
   return toDateString(new Date(Date.now() - n * 24 * 60 * 60 * 1000));
diff --git a/tests/types/dateString.test.ts b/tests/types/dateString.test.ts
new file mode 100644
index 0000000..3718263
--- /dev/null
+++ b/tests/types/dateString.test.ts
@@ -0,0 +1,41 @@
+import { describe, expect, it } from "vitest";
+import { kboTodayKst } from "../../src/types/dateString";
+
+// KST 벽시계 시각으로 Date를 만든다(UTC+09:00 명시). 실행 환경 TZ와 무관.
+function kst(iso: string): Date {
+  return new Date(`${iso}+09:00`);
+}
+
+describe("kboTodayKst — 새벽 03:00(KST) 컷오프", () => {
+  it("02:59이면 직전일 (일일 갱신 02:00 직후 버퍼)", () => {
+    expect(kboTodayKst(kst("2026-06-30T02:59:00"))).toBe("2026-06-29");
+  });
+
+  it("00:00(자정)이면 직전일", () => {
+    expect(kboTodayKst(kst("2026-06-30T00:00:00"))).toBe("2026-06-29");
+  });
+
+  it("03:00 정각이면 당일 (컷오프 경계 포함)", () => {
+    expect(kboTodayKst(kst("2026-06-30T03:00:00"))).toBe("2026-06-30");
+  });
+
+  it("03:01이면 당일", () => {
+    expect(kboTodayKst(kst("2026-06-30T03:01:00"))).toBe("2026-06-30");
+  });
+
+  it("정오면 당일", () => {
+    expect(kboTodayKst(kst("2026-06-30T12:00:00"))).toBe("2026-06-30");
+  });
+
+  it("23:59이면 당일", () => {
+    expect(kboTodayKst(kst("2026-06-30T23:59:00"))).toBe("2026-06-30");
+  });
+
+  it("월초 새벽이면 전월 말일로 넘어간다", () => {
+    expect(kboTodayKst(kst("2026-07-01T02:00:00"))).toBe("2026-06-30");
+  });
+
+  it("연초 새벽이면 전년 말일로 넘어간다", () => {
+    expect(kboTodayKst(kst("2026-01-01T01:00:00"))).toBe("2025-12-31");
+  });
+});