• Sargassum C.A. Agardh, 1820
• Sargassum abbottiae G.C. Trono, Jr., 1994
• Sargassum acanthicarpum Greville, 1848 accepted as Sargassum erinaceum Greville ex Kuntze, 1880
• Sargassum acanthicarpum Suhr, 1836 accepted as Sargassum lacerifolium (Turner) C. Agardh, 1820
• Sargassum acanthocarpum Suhr, 1836 accepted as Sargassum lacerifolium (Turner) C. Agardh, 1820
• Sargassum aciculare Grunow, 1874 accepted as Sargassum filifolium (C. Agardh) C. Agardh, 1824
• Sargassum acinacifolium Setchell & N.L. Gardner, 1924
• Sargassum acinaciforme Montagne, 1850
• Sargassum acinaria C. Agardh, 1821
• Sargassum acinarium (Linnaeus) Setchell, 1933
• Sargassum acutifolium Greville, 1849 accepted as Sargassum swartzii C. Agardh, 1820
• Sargassum aemulum Sonder, 1853 accepted as Sargassum distichum Sonder, 1845
• Sargassum affine J.G. Agardh accepted as Sargassum filipendula C. Agardh, 1824
• Sargassum agardhianum Farlow, 1889
• Sargassum agaviforme Tseng & Lu, 1994
• Sargassum albemarlense W.R. Taylor, 1945
• Sargassum albertisii Piccone, 1884
• Sargassum alternato-pinnatum Yamada, 1942
• Sargassum amabile Yamada, 1942
• Sargassum amaliae Grunow, 1874
• Sargassum ambiguum Sonder, 1871 accepted as Sargassum polycystum C. Agardh, 1824
• Sargassum amigdalifolium Bory de Saint-Vincent, 1832
• Sargassum ammophilum Yoshida & T. Konno, 1982
• Sargassum anapense Setchell & N.L. Gardner, 1901
• Sargassum angii L.M. Laio, 1998
• Sargassum angustifolioides Tseng & Lu, 2004
• Sargassum angustifolium C. Agardh, 1820
• Sargassum aperifolium Hering & G. Martens ex J.G. Agardh
• Sargassum aquifolium (Turner) C. Agardh, 1820
• Sargassum araii Yoshida, 1994
• Sargassum armatum J.G. Agardh, 1848
• Sargassum arnaudianum Montagne, 1850
• Sargassum asperifolium Hering & G. Martens ex J.G. Agardh, 1848
• Sargassum assimile Harvey, 1859
• Sargassum asymmetricum E.Y. Dawson, 1944 accepted as Sargassum alternato-pinnatum Yamada, 1942
• Sargassum asymmetricum Yamada, 1942 accepted as Sargassum alternato-pinnatum Yamada, 1942
• Sargassum autumnale Yoshida, 1983
• Sargassum bacciferum (Turner) C. Agardh, 1820 accepted as Sargassum natans (Linnaeus) Gaillon, 1828
• Sargassum baccularia (Mertens) C. Agardh, 1824
• Sargassum balingasayense Trono, 1994
• Sargassum banyuejiaoense C.K. Tseng & Lu, 1996
• Sargassum bataanense G.C. Trono, 1994
• Sargassum beihaiense C.K. Tseng & B. Lu, 1999
• Sargassum belangeri Bory de Saint-Vincent, 1834
• Sargassum berberifolium J.G. Agardh, 1848 accepted as Sargassum cristaefolium C. Agardh, 1820
• Sargassum bermudense Grunow, 1916
• Sargassum bicorne J.G. Agardh, 1848
• Sargassum biforme Sonder, 1845 accepted as Sargassum tristichum Sonder, 1845
• Sargassum binderi Sonder ex J.G. Agardh, 1848 accepted as Sargassum aquifolium (Turner) C. Agardh, 1820
• Sargassum biserrula J.G. Agardh, 1848
• Sargassum biserrulioides C.K. Tseng & Lu Baroen, 2002
• Sargassum biserrulum accepted as Sargassum biserrula J.G. Agardh, 1848
• Sargassum boraborense (Grunow) Setchell, 1926 accepted as Sargassum pacificum Bory de Saint-Vincent, 1828
• Sargassum boreale Yoshida & Horiguchi, 2000
• Sargassum boryanum A. Richard, 1834
• Sargassum boryanum Montagne, 1846 accepted as Sargassum trichocarpum J.G. Agardh, 1889
• Sargassum boryi C. Agardh, 1824
• Sargassum botruosum Montagne, 1850
• Sargassum botuliforme Kraft, 2009
• Sargassum boveanum J.G. Agardh, 1848
• Sargassum brachycarpum J.G. Agardh, 1889
• Sargassum brachyphyllum Zanardini, 1874
• Sargassum bracteolosum J.G. Agardh, 1889 accepted as Sargassum fallax Sonder, 1845
• Sargassum brandegeei Setchell & N.L. Gardner, 1924
• Sargassum brevifolium Greville, 1849 accepted as Sargassum polycystum C. Agardh, 1824
• Sargassum brevifolium Kützing, 1849 accepted as Sargassum duplicatum Bory de Saint-Vincent, 1828 accepted as Sargassum cristaefolium C. Agardh, 1820
• Sargassum brevipes Kützing, 1861 accepted as Sargassum vulgare C. Agardh, 1820
• Sargassum bryantii Setchell & Gardner, 1924
• Sargassum bulbiferum Yoshida, 1994
• Sargassum buxifolium (Chauvin) M.J. Wynne, 2011
• Sargassum californicum (Grunow) Setchell, 1937
• Sargassum calophyllum De Notaris, 1858
• Sargassum camouii E.Y. Dawson, 1944
• Sargassum campbellianum Greville, 1848 accepted as Sargassum tenerrimum J.G. Agardh, 1848
• Sargassum capillare Kützing, 1843
• Sargassum capilliforme Tseng & Lu, 1994
• Sargassum capitatum Tseng & Lu, 2002
• Sargassum carpophyllum J.G. Agardh, 1848
• Sargassum cavernulosum Kraft, 2009
• Sargassum cervicorne Greville, 1849
• Sargassum chamissonis Kützing
• Sargassum cheirifolium Kützing, 1849
• Sargassum cinctum J.G. Agardh, 1848
• Sargassum cinereum J.G. Agardh, 1848
• Sargassum cinotum J.G. Agardh
• Sargassum claviferum J.G. Agardh, 1889
• Sargassum clonocarpum Grunow, 1889
• Sargassum coarctatum Kützing, 1843 accepted as Sargassum vulgare C. Agardh, 1820
• Sargassum comosum Montagne, 1841 accepted as Sargassum desfontainesii (Turner) C. Agardh, 1820
• Sargassum compactum Bory de Saint-Vincent, 1828 accepted as Sargassum ilicifolium (Turner) C. Agardh, 1820
• Sargassum compactum Zanardini, 1874 accepted as Sargassum brachyphyllum Zanardini, 1874
• Sargassum concinnum Greville ex J.G. Agardh, 1848
• Sargassum confusum C. Agardh, 1824
• Sargassum congkinhii Pham-Hoàng Hô, 1967
• Sargassum corderoi R.B. Modelo Jr, I. Umezaki & L.M. Liao, 1998
• Sargassum coreanum J.G. Agardh, 1889
• Sargassum coriifolium J.G. Agardh, 1889 accepted as Sargassum odontocarpum Sonder, 1871
• Sargassum cornigerum Sonder, 1915
• Sargassum cornutifructum H.D. Nguyen & Q.N. Huynh, 1999
• Sargassum corynecarpum Harvey, 1860 accepted as Sargassum siliquastrum (Turner) C. Agardh, 1820