Chill a Champagne flute in the freezer until cold, about 10 minutes; keep the orange juice and Champagne refrigerated until very cold.
Pour the chilled orange juice into the cold flute, letting any bubbles settle briefly.
Top slowly with the chilled Champagne, angling the glass to minimize foaming and preserve carbonation; stop when the glass is nearly full and the drink looks lightly effervescent.
Express the orange peel over the drink to release oils, twist, and place on the rim or float on top; serve immediately while well-chilled.