London Broncos' brave bid to retain their Super League status came up short, while Salford Red Devils claimed third place in the table.
Richard Agar stepped into an interim coaching role with Leeds Rhinos in May and has now earned a 12-month rolling deal.
Jay Pitts' late try means London Broncos remain in with a chance of beating the drop, while also leaving Hull KR in deep trouble.
A 36-10 win over London Broncos means Leeds Rhinos can put a forgettable Super League campaign behind them and not worry about relegation.
Super League leaders St Helens put in an impressive second-half display as they stormed to a 36-20 victory over Leeds Rhinos at Headingley.
Leeds Building Society have gifted their shirt sponsorship to Samaritans for the Rhinos' Super League clash with St Helens on Thursday.
Leeds Rhinos moved four points clear of 12th-place London Broncos by thrashing Catalans Dragons on Friday, despite having a man sent off.
The clinical Ash Handley has agreed a new deal to remain at Headingley until at least 2023.
Huddersfield Giants were torn apart by struggling Leeds Rhinos at their own ground in Super League on Friday.
St Helens have only lost three games all year in Super League, but two of those defeats have come at London Broncos.