A five-wicket haul to Wagner ripped through Bangladesh to dismiss them for 234.
Tamim Iqbal brought up his ninth Test century in an heroic one-man stand for Bangladesh.
Tamim Iqbal was 86 not out as Bangladesh made light of the conditions and New Zealand's reputation to dominate the opening session of the first Test.
The overwhelming victory gave New Zealand the series 1-0 after the first Test in Wellington was drawn.
New Zealand completed their demolition of Sri Lanka, needing only 14 balls to take the last three wickets for a colossal 423-run victory.
The conditions were tailor-made for short-ball specialist Wagner, New Zealand bowling coach Shane Jurgensen said, as Sri Lanka were 231 for six at stumps.
New Zealand were eyeing an historic victory as injury and a barrage of Neil Wagner bouncers left Sri Lanka in tatters at the close of day four of the second Test in Christchurch on Saturday.
Neil Wagner captured the wicket of in-form Sri Lanka batsman Kusal Mendis to revive New Zealand‘s spirits as they fought to wrap up the series-deciding second Test in Christchurch on Saturday. Sri Lanka were also hampered by an injury to Angelo Mathews who appeared to tweak a hamstring and could only hobble for the last...
Sri Lanka's Kusal Mendis posted his eighth Test 50 as he battled with captain Dinesh Chandimal to save the second Test against New Zealand on day four in Christchurch Saturday.
In December 2017 against West Indies at Basin Reserve, Wagner claimed career-best figures.