Synonyms of happily

2 Syllables
lightly, gladly, freely, brightly, joyously, buoyantly, gaily
3 Syllables
willingly, triumphantly, lovingly, merrily, cheerfully, enjoyably, jauntily, swimmingly, cosily, pleasantly, winningly, nicely, amiably, heartily, zestfully, agreeably, jovially, mirthfully, playfully, blissfully, blithely, gleefully, joyfully, graciously, laughingly, smilingly
4 Syllables
devotedly, desirably, pleasurably, satisfyingly, delightfully, sincerely, welcomely, effortlessly, amicably, peacefully, vivaciously, contentedly, delightedly, elatedly, exultantly, hilariously, lightheartedly, sportively, prosperously
5 Syllables
goodhumoredly, fortunately
6 Syllables
enthusiastically, affirmatively, exhilaratingly, optimistically