Williamson (70*) notched his maiden fifty in IPL 2019.
The Kiwi international also slammed his 12th career IPL fifty.
The SRH skipper smashed five fours and four sixes.
He needs six more maximums to get to the mark of 50 in IPL.
Williamson hit the 700th six of this season off Umesh Yadav's bowling in the 20th over.
Chahal first player to take 100 wickets for RCB
Yuzvendra Chahal finished with 18 wickets in IPL 2019. It was his third best tally of wickets in a season. The Indian cricketer became the first player to take 100 wickets for RCB. He also became the 14th player to take 100 scalps in IPL.
SRH got off to a flier, before losing three quick wickets.
Williamson and Vijay Shankar added a crucial 43-run stand next.
RCB hit back to to reduce the side to 139/7 and had the match under control.
But Umesh Yadav's horrible final over saw SRH maximize.
In reply, SRH pacers sent RCB's top order back to the hut, before Hetmyer batted beautifully.
Hetmyer and Gurkeerat smash a new record for RCB
Hetmyer and Gurkeerat Singh Mann shared a 100-plus stand for RCB tonight. This was the first 100-plus partnership for RCB not involving Kohli or AB de Villiers since 2013. Chris Gayle and Cheteshwar Pujara had shared 102-run stand against Kings XI Punjab that year.