diff --git a/icu4c/source/common/unames.cpp b/icu4c/source/common/unames.cpp
index e6fa30f3bd9..a2035c48dfc 100644
--- a/icu4c/source/common/unames.cpp
+++ b/icu4c/source/common/unames.cpp
@@ -1554,15 +1554,16 @@ u_charFromName(UCharNameChoice nameChoice,
         *pErrorCode = U_ILLEGAL_CHAR_FOUND;
         return error;
     }
+    // i==strlen(name)==strlen(lower)==strlen(upper)
 
     /* try extended names first */
     if (lower[0] == '<') {
         if (nameChoice == U_EXTENDED_CHAR_NAME) {
-            if (lower[--i] == '>') {
-                for (--i; lower[i] && lower[i] != '-'; --i) {
-                }
+            // Parse a string like "<category-HHHH>" where HHHH is a hex code point.
+            if (lower[--i] == '>' && i >= 3 && lower[--i] != '-') {
+                while (i >= 3 && lower[--i] != '-') {}
 
-                if (lower[i] == '-') { /* We've got a category. */
+                if (i >= 2 && lower[i] == '-') {
                     uint32_t cIdx;
 
                     lower[i] = 0;
diff --git a/icu4c/source/test/cintltst/cucdtst.c b/icu4c/source/test/cintltst/cucdtst.c
index 72feba8c522..b7ea2740440 100644
--- a/icu4c/source/test/cintltst/cucdtst.c
+++ b/icu4c/source/test/cintltst/cucdtst.c
@@ -49,6 +49,7 @@ static void TestCodeUnit(void);
 static void TestCodePoint(void);
 static void TestCharLength(void);
 static void TestCharNames(void);
+static void TestUCharFromNameUnderflow(void);
 static void TestMirroring(void);
 static void TestUScriptRunAPI(void);
 static void TestAdditionalProperties(void);
@@ -183,6 +184,7 @@ void addUnicodeTest(TestNode** root)
     addTest(root, &TestControlPrint, "tsutil/cucdtst/TestControlPrint");
     addTest(root, &TestIdentifier, "tsutil/cucdtst/TestIdentifier");
     addTest(root, &TestCharNames, "tsutil/cucdtst/TestCharNames");
+    addTest(root, &TestUCharFromNameUnderflow, "tsutil/cucdtst/TestUCharFromNameUnderflow");
     addTest(root, &TestMirroring, "tsutil/cucdtst/TestMirroring");
     addTest(root, &TestUScriptCodeAPI, "tsutil/cucdtst/TestUScriptCodeAPI");
     addTest(root, &TestHasScript, "tsutil/cucdtst/TestHasScript");
@@ -1937,6 +1939,35 @@ TestCharNames() {
     /* ### TODO: test error cases and other interesting things */
 }
 
+static void
+TestUCharFromNameUnderflow() {
+    // Ticket #10889: Underflow crash when there is no dash.
+    UErrorCode errorCode=U_ZERO_ERROR;
+    UChar32 c=u_charFromName(U_EXTENDED_CHAR_NAME, "<NO BREAK SPACE>", &errorCode);
+    if(U_SUCCESS(errorCode)) {
+        log_err("u_charFromName(<NO BREAK SPACE>) = U+%04x but should fail - %s\n", c, u_errorName(errorCode));
+    }
+
+    // Test related edge cases.
+    errorCode=U_ZERO_ERROR;
+    c=u_charFromName(U_EXTENDED_CHAR_NAME, "<-00a0>", &errorCode);
+    if(U_SUCCESS(errorCode)) {
+        log_err("u_charFromName(<-00a0>) = U+%04x but should fail - %s\n", c, u_errorName(errorCode));
+    }
+
+    errorCode=U_ZERO_ERROR;
+    c=u_charFromName(U_EXTENDED_CHAR_NAME, "<control->", &errorCode);
+    if(U_SUCCESS(errorCode)) {
+        log_err("u_charFromName(<control->) = U+%04x but should fail - %s\n", c, u_errorName(errorCode));
+    }
+
+    errorCode=U_ZERO_ERROR;
+    c=u_charFromName(U_EXTENDED_CHAR_NAME, "<control-111111>", &errorCode);
+    if(U_SUCCESS(errorCode)) {
+        log_err("u_charFromName(<control-111111>) = U+%04x but should fail - %s\n", c, u_errorName(errorCode));
+    }
+}
+
 /* test u_isMirrored() and u_charMirror() ----------------------------------- */
 
 static void