Victory over second-placed Malton and Norton saw Doncaster Phoenix complete their perfect season in Yorkshire One, winning all 26 of their games.
Malton got off to a good start, scoring and converting early on.
But on 18 minutes Dave Hankinson slotted over a penalty for Phoenix and Craig Deakin ran in a try with Hankinson on target again to make it 10-10 at the break.
The second half was one-way traffic as Phoenix stepped up a gear and Nick Byrne and Tim Elliot crashed over with Ryan Peacey scoring a brace.
Phoenix are promoted as champions and will play in North One East next season.
There was no such luck for relegated Wath on Dearne, who lost their final Yorkshire One match at Pontefract 44-17.
Wheatley Hills’ season ended on a disappointing note when they lost out 32-29 at home to North One East rivals Old Crossleyans.
The Doncaster side were challenging for promotion up until Christmas and had lost just three games but a disastrous run of form since then saw them finish eighth in the table.
A Jonathan Woodcock penalty in the 17th minute gave Wheatley the lead, but three first half tries gave the visitors a 17-10 lead going into the break, with Thomas White scoring the hosts’ only try of the half.
Tom White completed his hat trick in the second half, with Woodcock converting three of his team’s tries, but it was not enough to avoid defeat as Old Crossleyans scored a further two tries in the second half.
Thornensians secured third spot in Yorkshire Three with an emphatic nine-try victory at Harrogate Pythons, winning 22-59.
Ryan Pilley and Rob Moffatt scored two tries each, while others came from Lee Linsdell, Olly Cox, Ryan Russell, Aaron Holt and Adam Smith.
Cox kicked six of the conversions, while Josh Walker was on target with one.