The Eagles followed up last Sunday's 54-12 play-off win at Halifax with a 32-22 victory over Leigh at Leigh Sports Village in the final eliminator.
Sheffield were forced to withstand a brave fightback by their hosts, who had trailed 26-6.
The visitors made the perfect start with second rower Michael Knowles scoring the first try inside the first minute before Leigh had touched the ball, and they led 18-0 after half-an-hour courtesy of further scores from winger Misi Taulapapa and centre Dane Straugher.
Winger Jonathan Pownall gave the Centurions hope with a 37th-minute try but Simon Brown kicked a penalty on the stroke of half-time to make it 20-4, and winger Scott Turner stretched Sheffield's lead with a fourth try early in the second half.
Second rower Andy Thornley gave Leigh renewed hope with a 50th-minute try and substitutes Ryan Brierley and Dean McGilvray added others in the last eight minutes to set up a tense finish, but Sheffield centre Menzie Yere sealed it with a last-minute try.
- Leigh Sports Village