This volume contains full versions of selected papers presented at the 28th International Workshop on Combinatorial Algorithms (IWOCA) held 17–21 July 2017 in Newcastle, Australia, sponsored by Priority Research Centre for Computer Assisted Research Mathematics and its Applications (CARMA) and the School of Electrical Engineering & Computing, The University of Newcastle, with support from the European Association for Theoretical Computer Science. At that meeting, 30 papers were presented, chosen after careful review from a total of 66 submissions. These contributions, together with five papers based on invited presentations to the meeting, were published in the IWOCA 2017 Proceedings (Springer Lecture Notes in Computer Science LNCS 10765). In this collection 14 articles are published, the result of a second, rigorous refereeing of substantially extended versions of conference papers.