Kimber made his first-class debut in March 2019.
Before this game, his best first-class score was 104 and he had only made two centuries for the first team, the other coming in 50-over cricket.
But he scored 141 off 120 balls as an opener in a second XI fixture against Notts earlier this month.
And, against Sussex, as well as breaking the Championship record for most runs in an over by smashing Robinson to all parts, he set other new milestones too.
Kimber scored the fastest Championship double hundred from balls faced (100), obliterating Aneurin Donald’s 123-ball mark for Glamorgan against Derbyshire in 2016.
His 21 sixes broke Ben Stokes’ Championship record of 17 set for Durham against Worcestershire in 2022.
Kimber also holds records at National Counties – also known as minor counties – level, including the biggest score in their T20 competition, having made 162 from 55 balls, including 12 fours and 15 sixes for Lincolnshire against Northumberland in 2018.
He also holds the record for Lincolnshire’s highest score in the National Counties Championship – compiling 246 against Hertfordshire at Hertford in 2019.
Leicestershire began the final morning on 139-5 – still 325 runs shy of victory with just five wickets in hand – and Kimber was initially circumspect.
He scored 26 off his first 30 balls before a calculated assault on off-spinner Jack Carson, whom he hit for 20 in an over, took him to a 37-ball half-century.
Kimber’s stand of 239 in 27 overs with Ben Cox (34) – a new Leicestershire eighth-wicket record – ended when Robinson pinned the latter with an in-swinger.
When Ben Mike lobbed up a simple catch to mid-off, Leicestershire needed 29 to win and Kimber had no option but to go for broke. His 21st six off Robinson sailed over long on but in the next over McAndrew had the final word.
Relieved Sussex head coach Paul Farbrace said: “He hit 21 sixes but it felt like 41 and I’m not surprised at the records he has broken. It was an exceptional innings – but our session after lunch when we took the last three wickets was top class.”