In 1584, Tadaoki took part in the Battle of Komaki Nagakute, and in the following year (1585) he was promoted to the rank of Jushiinoge (Junior Forth Rank, Lower Grade), appointed to the position of Jiju (chamberlain) and given the family name "Hashiba" by Hideyoshi (this name continued to be used until the end of Osaka Natsu no Jin (Summer Siege of Osaka)).
天正12年（1584年）の小牧・長久手の戦いに参加し、翌13年（1585年）には従四位下、侍従に叙任し、秀吉から羽柴姓を与えられた（大坂夏の陣終了後まで羽柴姓を継続）。