Williamson plundered 28 runs in the final over, dealing with fours and sixes. SRH were in trouble after losing early wickets. Sent into bat, Martin Guptill and Wriddhiman Saha (20) put on 46 runs for the opening wicket in 4.3 overs but after that they lost quick wickets.
However, Williamson cut loose after the 19th over, smashing Umesh Yadav for two sixes and as many fours to finish the innings on a high.
Manish Pandey, who emerged as the hero in the previous game against Mumbai Indians with his brave half century in their last game, fell cheaply, for nine, leaving the visitors in some trouble at 61 for three in the eighth over.
Picked in the World Cup bound Indian team for his 'three-dimensional' abilities, Vijay Shankar raced to 27 with the help of three sixes, but again failed to translate the start into a big score.
Shankar was Sundar's third scalp of the evening and Yuzvendra Chahal picked up his 100th wicket in IPL when he lured Yusuf Pathan into playing an irresponsible shot to leave Sunrisers at 127 for five in the final ball of 16th over.
Even as wickets fell at regular intervals, Williamson looked to rotate the strike and also go for the big hits.
Barring the opening stand, the only partnership that flourished a bit was the one between Williamson and Shankar, who ended up giving a catch while going for a slog sweep.
Williamson brought up his fifty in style, hoicking Yadav over long off for a six and followed that with some more lusty hits.