diff --git a/Libraries/LibWeb/CSS/StyleValues/CalculatedStyleValue.cpp b/Libraries/LibWeb/CSS/StyleValues/CalculatedStyleValue.cpp
index ced6911d3f1..87df71bc3b1 100644
--- a/Libraries/LibWeb/CSS/StyleValues/CalculatedStyleValue.cpp
+++ b/Libraries/LibWeb/CSS/StyleValues/CalculatedStyleValue.cpp
@@ -2362,6 +2362,55 @@ Optional<CalculatedStyleValue::CalculationResult> RoundCalculationNode::run_oper
     auto a = maybe_a->value();
     auto b = maybe_b->value();
 
+    // https://drafts.csswg.org/css-values-4/#round-infinities
+    // In round(A, B), if B is 0, the result is NaN. If A and B are both infinite, the result is NaN.
+    if (b == 0 || (isinf(a) && isinf(b)))
+        return CalculatedStyleValue::CalculationResult { AK::NaN<double>, consistent_type };
+
+    // If A is infinite but B is finite, the result is the same infinity.
+    if (isinf(a) && isfinite(b))
+        return CalculatedStyleValue::CalculationResult { a, consistent_type };
+
+    // If A is finite but B is infinite, the result depends on the <rounding-strategy> and the sign of A:
+    if (isfinite(a) && isinf(b)) {
+        FloatExtractor<double> const extractor { .d = a };
+
+        switch (m_strategy) {
+        // nearest, to-zero:
+        case RoundingStrategy::Nearest:
+        case RoundingStrategy::ToZero: {
+            // If A is positive or 0⁺, return 0⁺. Otherwise, return 0⁻.
+            return CalculatedStyleValue::CalculationResult { !extractor.sign ? 0.0 : -0.0, consistent_type };
+        }
+        // up:
+        case RoundingStrategy::Up: {
+            double result;
+            if (a > 0) {
+                // If A is positive(not zero), return +∞.
+                result = AK::Infinity<double>;
+            } else {
+                // If A is 0⁺, return 0⁺. Otherwise, return 0⁻.
+                result = !extractor.sign ? 0.0 : -0.0;
+            }
+
+            return CalculatedStyleValue::CalculationResult { result, consistent_type };
+        }
+        // down:
+        case RoundingStrategy::Down: {
+            double result;
+            if (a < 0) {
+                // If A is negative (not zero), return −∞.
+                result = -AK::Infinity<double>;
+            } else {
+                // If A is 0⁻, return 0⁻. Otherwise, return 0⁺.
+                result = extractor.sign ? -0.0 : 0.0;
+            }
+
+            return CalculatedStyleValue::CalculationResult { result, consistent_type };
+        }
+        }
+    }
+
     // If A is exactly equal to an integer multiple of B, round() resolves to A exactly (preserving whether A is 0⁻ or
     // 0⁺, if relevant).
     if (fmod(a, b) == 0)
diff --git a/Tests/LibWeb/Text/expected/wpt-import/css/css-values/round-mod-rem-computed.txt b/Tests/LibWeb/Text/expected/wpt-import/css/css-values/round-mod-rem-computed.txt
index e62e52e58f0..22714520331 100644
--- a/Tests/LibWeb/Text/expected/wpt-import/css/css-values/round-mod-rem-computed.txt
+++ b/Tests/LibWeb/Text/expected/wpt-import/css/css-values/round-mod-rem-computed.txt
@@ -2,8 +2,8 @@ Harness status: OK
 
 Found 229 tests
 
-211 Pass
-18 Fail
+215 Pass
+14 Fail
 Pass	round(10,10) should be used-value-equivalent to 10
 Pass	mod(1,1) should be used-value-equivalent to 0
 Pass	rem(1,1) should be used-value-equivalent to 0
@@ -217,18 +217,18 @@ Pass	round(to-zero, 0, -Infinity) should be used-value-equivalent to 0
 Pass	round(to-zero, 4, -Infinity) should be used-value-equivalent to 0
 Pass	round(to-zero, -0, -Infinity) should be used-value-equivalent to calc(-0)
 Pass	round(to-zero, -4, -Infinity) should be used-value-equivalent to calc(-0)
-Fail	round(up, 1, Infinity) should be used-value-equivalent to calc(Infinity)
+Pass	round(up, 1, Infinity) should be used-value-equivalent to calc(Infinity)
 Pass	round(up, 0, Infinity) should be used-value-equivalent to 0
 Pass	round(up, -1, Infinity) should be used-value-equivalent to calc(-0)
-Fail	round(up, 1, -Infinity) should be used-value-equivalent to calc(Infinity)
+Pass	round(up, 1, -Infinity) should be used-value-equivalent to calc(Infinity)
 Pass	round(up, 0, -Infinity) should be used-value-equivalent to 0
 Pass	round(up, -1, -Infinity) should be used-value-equivalent to calc(-0)
 Pass	round(down, 1, Infinity) should be used-value-equivalent to calc(-0)
 Pass	round(down, 0, Infinity) should be used-value-equivalent to 0
-Fail	round(down, -1, Infinity) should be used-value-equivalent to calc(-Infinity)
+Pass	round(down, -1, Infinity) should be used-value-equivalent to calc(-Infinity)
 Pass	round(down, 1, -Infinity) should be used-value-equivalent to calc(-0)
 Pass	round(down, 0, -Infinity) should be used-value-equivalent to 0
-Fail	round(down, -1, -Infinity) should be used-value-equivalent to calc(-Infinity)
+Pass	round(down, -1, -Infinity) should be used-value-equivalent to calc(-Infinity)
 Pass	mod(-0, Infinity) should be used-value-equivalent to calc(NaN)
 Pass	mod(0, -Infinity) should be used-value-equivalent to calc(NaN)
 Pass	mod(-4, Infinity) should be used-value-equivalent to calc(NaN)
diff --git a/Tests/LibWeb/Text/expected/wpt-import/css/css-values/signed-zero.txt b/Tests/LibWeb/Text/expected/wpt-import/css/css-values/signed-zero.txt
index 8ea30e4d765..f4af39bad35 100644
--- a/Tests/LibWeb/Text/expected/wpt-import/css/css-values/signed-zero.txt
+++ b/Tests/LibWeb/Text/expected/wpt-import/css/css-values/signed-zero.txt
@@ -2,8 +2,8 @@ Harness status: OK
 
 Found 162 tests
 
-154 Pass
-8 Fail
+156 Pass
+6 Fail
 Pass	sign(calc(-0)) should be used-value-equivalent to 0
 Pass	clamp(-1, 1 / sign(calc(-0)), 1) should be used-value-equivalent to -1
 Pass	sign(calc( 0)) should be used-value-equivalent to 0
@@ -79,7 +79,7 @@ Pass	clamp(-1, 1 / sign(round(nearest, -0, infinity)), 1) should be used-value-e
 Pass	sign(round(nearest,  0, infinity)) should be used-value-equivalent to 0
 Pass	clamp(-1, 1 / sign(round(nearest,  0, infinity)), 1) should be used-value-equivalent to 1
 Pass	sign(round(nearest,  1, infinity)) should be used-value-equivalent to 0
-Fail	clamp(-1, 1 / sign(round(nearest,  1, infinity)), 1) should be used-value-equivalent to 1
+Pass	clamp(-1, 1 / sign(round(nearest,  1, infinity)), 1) should be used-value-equivalent to 1
 Pass	sign(round(up, -1, infinity)) should be used-value-equivalent to 0
 Pass	clamp(-1, 1 / sign(round(up, -1, infinity)), 1) should be used-value-equivalent to -1
 Pass	sign(round(up, -0, infinity)) should be used-value-equivalent to 0
@@ -91,7 +91,7 @@ Pass	clamp(-1, 1 / sign(round(down, -0, infinity)), 1) should be used-value-equi
 Pass	sign(round(down,  0, infinity)) should be used-value-equivalent to 0
 Pass	clamp(-1, 1 / sign(round(down,  0, infinity)), 1) should be used-value-equivalent to 1
 Pass	sign(round(down,  1, infinity)) should be used-value-equivalent to 0
-Fail	clamp(-1, 1 / sign(round(down,  1, infinity)), 1) should be used-value-equivalent to 1
+Pass	clamp(-1, 1 / sign(round(down,  1, infinity)), 1) should be used-value-equivalent to 1
 Pass	sign(mod(-1, -1)) should be used-value-equivalent to 0
 Fail	clamp(-1, 1 / sign(mod(-1, -1)), 1) should be used-value-equivalent to -1
 Pass	sign(mod(-1,  1)) should be used-value-equivalent to 0