Kent were promoted to Specsavers County Championship Division One after wrapping up an emphatic victory over Glamorgan on a day that also saw Worcestershire's relegation from the top flight confirmed.
Kent won by an innings and 172 runs with five sessions to spare in Canterbury having bowled bottom side Glamorgan out for 78, with Darren Stevens claiming five for 24 and Matt Henry another four wickets, leaving him with eight in the match.
Their promotion was then sealed as Sussex, third in Division Two, failed to secure maximum batting bonus points in their clash with second-placed Warwickshire at Hove.
Kent captain Sam Billings said: "I've never played first division Championship cricket and it's always been my ambition, so I'm tremendously proud that this team has taken Kent back to the level of English cricket that this great club feels it belongs at.
"It's been a monumental effort from everyone in the club."
Warwickshire are themselves closing in on joining Kent in Division One next season. Bad light brought a premature end to the day at Hove with the Bears 141 for none, giving them a lead of 238 in a game they only need to draw to seal their promotion.
Having dismissed fellow promotion-chasers Sussex for 343 for nine - with Tom Haines unfit to bat - Warwickshire's opening pair of Will Rhodes and Dom Sibley piled on the runs to move them to the brink of an immediate return to the top flight.
Sussex's own hopes of promotion became increasingly far-fetched as the day progressed.
Worcestershire, who were promoted to the top tier last season, dropped back down to Division Two with a heavy loss to Essex at Chelmsford.
Jamie Porter was the away side's chief destroyer as the Pears were beaten by an innings and 129 runs, the 25-year-old ending the second innings with figures of four for 57 to earn himself a match haul of 11 for 98.
Simon Harmer also chipped in with four for 76 as Worcestershire were bowled out for 251. It was a quick return to earth for the county, five days after winning the Vitality Blast.
Yorkshire's Adam Lyth registered a century on a rain-affected third day against Hampshire, whose Division One safety was mathematically confirmed by Worcestershire's defeat at Essex.
Lyth advanced from 60 overnight to 134 not out as Yorkshire, leading by 27 after the first innings, moved from 172 for four to 287 for five at Headingley, where there was no more play possible after rain arrived during the lunch break.
If Yorkshire win they will also be mathematically safe from relegation.
Related cricket links
