Harry Scowen (69) and wicketkeeper Jake Woolley (50) lead the Hastings charge in the first innings, while Eastbourne captain Jacob Smith took 3-19.
The reply saw Adam Barton (3-26) and Dilshan De Zoysa (3-40) perform commendably with the ball.
The victory, their fourth in a row, saw Hastings finish 16 points and two places clear of second-from-bottom Cuckfield, who pulled off a remarkable 109-run win at recently-crowned champions Preston Nomads.
A trio of fine knocks from Nipun Karunanayake (54), Ollie Graham (58), and Harry Clark (a run-a-ball 61) propelled Cuckfield to 223-8 off their allotted 50 overs.
Karunanayake then took 3-16 as Nomads were bowled out for 114.
Cuckfield recorded 28 points for the win, but it wasn't enough for them to secure Premier Division survival.
The Mid Sussex outfit finished just four points adrift of third-from-bottom Brighton & Hove, who were beaten by three-wickets at third-placed Roffey.
An unbeaten 60 from wicketkeeper Adam Mate took Brighton to 206-7 off their allotted overs.
But, despite the best efforts of Brighton bowler Ryan Chase (3-44), the Boars reached the target, for the loss of seven wickets, in 38.5 overs.
Premier Division runners-up East Grinstead (192 all out) suffered a 10-run defeat at Middleton (202 all out).
Mahesh Rawat (60 off 57 balls) top-scored for Middleton, while Lewis Hatchett (4-50) did the damage for EG.
Opener Will Adkin (65) starred for the visitors, but Sam Green (3-25) and Rawat (3-28) helped bowl Middleton to victory.
Fourth-placed Three Bridges (161 all out) picked up a 24-run win at home to already-relegated Haywards Heath (137 all out).
Ollie Bailey took 3-28 for Heath in the first innings, while Bridges' Conor Golding finished with figures of 3-38 in the second.
In Division 2, Horsham secured promotion back to the Premier Division at the first time of asking.
The Lions (92-3) recorded a convincing seven-wicket home victory over Burgess Hill (88 all out) to secure second.
Sussex star Will Beer blew the Hill away with the ball, finishing his spell with astonishing figures of 6-30.
Beer then hit an unbeaten 52 to power the hosts to victory in 19 overs, despite resistance from Hill's Dan Strange (3-40).
The victory saw Horsham finish 44 points clear of third-placed St James' Montefiore, who fell to a two-wicket loss at home to champions Bognor Regis.
Hector Laughton's 61 off 59 balls was matched by Joe Ashmore's 4-47 for Bognor, as the hosts scored 205-9 off their 50 overs.
Two wonderful batting performances from Ashmore (70 not out) and wicketkeeper and captain Ryan Maskell (62 off 58 balls) propelled Bognor to 209-8 in 40.2 overs to win the game.
At the other end of the table, Lindfield (106-3) saw off bottom club Roffey 2nd XI (105 all out) to beat the Division 2 drop.
Scott Pedley (3-13) and Harry Chaudhary (3-18) bowled well for the Swans in the first innings.
Lindfield finished the season in seventh, 16 points clear of place-below Billingshurst and 30 ahead of second-from-bottom Preston Nomads 2nd XI, who were both relegated on the final day despite winning.
Billingshurst (153-8) recorded a two-wicket win away at fourth-placed Mayfield (151 all out).
Benjamin Mortimer (4-31) excelled with the ball for Hurst, before Josh Wood blasted a magnificent quick-fire 67 off 31 balls for the visitors.
Preston Nomads 2nd XI (152 all out) also won on the road, seeing off Chichester Priory Park (120 all out) by 32 runs.
Ajit Sambhi (3-7) was as devastating with the ball as he was economical for Chi in the first innings.
Opener Tim Wergen (65) got Chi off to a strong start, but a devastating spell from Ravi Jadav (5-26) fired Nomads to victory.
Other notable performances and confirmed promotion and relegation:
Division 3 West: Bradley Bridson 5-49 for Findon.
West Chiltington & Thakeham are champions, Findon will enter the Division 3 promotion play-off, Goring By Sea and Henfield have been relegated.
Division 3 East: Atif Ali 5-12 for Crawley Eagles. Ben Barter 92 off 64 balls for Eastbourne 2nd XI. Jani Flind 5-61 for Glynde & Beddingham.
St Peters are champions, Rye will enter the Division 3 promotion play-off, Eastbourne 2nd XI and Brighton & Hove 2nd XI have been relegated.
Division 4 West: Hywel Jones 116 for Steyning.
Steyning are champions, Chippingdale promoted, East Preston, Chichester Priory Park 2nd XI and Stirlands have been relegated.
Division 4 East: David Rayment 153 off 124 balls for Crowhurst Park. Craig Olive 6-29 for Buxted Park. George Ledden 150 off 138 balls for Rottingdean.
Crowhurst Park are champions, Buxted Park promoted, Lewes Priory, Keymer & Hassocks and Isfield have been relegated.
Division 5 West: Joseph Sissons 5-41 for West Wittering.
Middleton 2nd XI are champions, West Wittering promoted, Clymping and Billingshurst 2nd XI have been relegated.
Division 5 Central: Joshith G 111 not out off 59 balls for Dome Mission.
Three Bridges 2nd XI are champions, Dome Mission promoted, Fletching and Ansty 2nd XI have been relegated.
Division 5 East: Little Common Ramblers are champions, Hailsham promoted, Willingdon and Hellingly have been relegated.
Division 6 West: Irsan Mohamed 5-45 for Crawley Eagles 2nd XI. Justin Scott 7-26 for Pagham 2nd XI. Ed White 101 not out off 78 balls for West Chiltington & Thakeham 2nd XI.
Rustington are champions, West Chiltington & Thakeham 2nd XI promoted, Eastergate and Broadbridge Heath have been relegated.
Division 6 Central: Hamish Nolan 113 and William Heine 118 not out for Ditchling.
Burgess Hill 2nd XI are champions, St Andrews promoted, Dormansland and Preston Nomads 3rd XI have been relegated.
Division 6 East: Tom Glenn 100 off 91 balls for Laughton.
Herstmonceux are champions, Pett promoted, Laughton and Rye 2nd XI have been relegated.
Division 7 West: Bognor Regis 2nd XI are champions, Slinfold 2nd XI promoted, Stirlands 2nd XI and Selsey have been relegated.
Division 7 Central: St Matthias are champions, Scaynes Hill are promoted, Portslade 2nd XI and Smallfield Manor have been relegated.
Division 7 East: Tunbridge Wells 3rd XI are champions, Robertsbridge promoted, Maresfield and Tunbridge Wells Borderers have been relegated.
Division 8 West: Chichester Priory Park 3rd XI are champions, Roffey 3rd XI promoted, Horsham 3rd XI and Ifield 3rd XI have been relegated.
Division 8 Central: Mark Botha 145 off 116 balls for Felbridge & Sunnyside 2nd XI. Kuganesh Karuppiah 121 for Forest Row.
Felbridge & Sunnyside 2nd XI are champions, Palmers promoted, Plumpton & East Chiltington and Cowden have been relegated.
Division 8 East: Hailsham 2nd XI are champions, Eastbourne 3rd XI promoted, Lewes St Michaels and Bexhill 3rd XI have been relegated.
Division 9 West: Liam Kitchener 110 for Chippingdale 2nd XI.
Chippingdale 2nd XI are champions, Bosham promoted, Wisborough Green 2nd XI and Horsham Trinity 2nd XI have been relegated.
Division 9 Central: Steve Pollard 109 for Colemans Hatch.
Coleman Hatch are champions, Three Bridges 3rd XI promoted, Lindfield 3rd XI and Brunswick Village have been relegated.
Division 9 East: Callum Lainchbury 5-25 for Hellingly 2nd XI.
St Peters 3rd XI are champions, Little Common Rambles 2nd XI promoted and Ringmer 2nd XI and Hellingly 2nd XI have been relegated.
Division 10 West: Paul Allwright 5-56 for Chippingdale 3rd XI. Matthew Peskett 5-23 for Southwater 2nd XI. Ross Lucas 146 for West Chiltington & Thakeham 3rd XI.
West Chiltington & Thakeham 3rd XI are champions, Tilgate promoted, Worthing 3rd XI, Chippingdale 3rd XI, Ram 3rd XI and Billingshurst 3rd XI have been relegated.
Division 10 Central: William Broyd 7-20 for Ditchling 2nd XI. Matthew Britt 100 not out and Joseph Abdool 123 off 120 balls for Lingfield 3rd XI. Jonathan Terry 102 for Crawley Down 2nd XI. Pete Atkins 5-26 for Poynings 2nd XI.
Burgess Hill 3rd XI are champions, Edenbridge 2nd XI promoted, Crawley Down 2nd XI, Poynings 2nd XI, Balcombe 2nd XI and Ansty 4th XI have been relegated.
Division 10 East: Chris Turner 5-16 for Blackboys. Sam Aldis 5-24 for Nutley. Simon Routh 105 not out for Tunbridge Wells 4th XI.
Selmeston & Alciston are champions, Westfield promoted, Blackboys, Willingdon 2nd XI, Linden Park 4th XI and Seaford 3rd XI have been relegated.
Division 11 West (North): Rudgwick are champions, Ifield 4th XI promoted, Barns Green 3rd XI and Horsham Trinity 3rd XI have been relegated.
Division 11 West (South): Middleton 3rd XI are champions, Pagham 3rd XI promoted, Clymping 2nd XI and Aldwick 2nd XI have been relegated.
Division 11 Central (North): Adam Galbraith 147 off 78 balls and Dominic Smith 5-22 for Mid Sussex Heathens. Andrew Angelow Thilagarajan 5-14 for Forest Row 2nd XI.
Haywards Heath 3rd XI are champions, Newick 2nd XI promoted, Forest Row 2nd XI and Balcombe 3rd XI have been relegated.
Division 11 Central (South): John Webster 105 for Streat & Westmeston 2nd XI.
Hurstpierpoint 2nd XI are champions, St James's Montefiore 3rd XI promoted, Streat & Westmeston 2nd XI and Southwick 2nd XI have been relegated.
Division 11 East (North): Sam Williams 106 and Jamie Cornford 5-42 for Burwash Weald. Oliver Pinder 105 for Chiddingly 2nd XI.
Wadhurst are champions, Buxted Park 3rd XI promoted, Uckfield Anderida 2nd XI and Isfield 2nd XI have been relegated.
Division 11 East (South): Sameera Dissanayake 117 for Hastings & St Leonards Priory 3rd XI. Lekhan Mestha 6-32 and Cameron Flanagan 103 not out off 101 balls for Crowhurst Park 3rd XI. Dominic Simes 99 off 77 balls for Pevensey 2nd XI.
Hastings & St Leonards Priory 3rd XI are champions, Sidley promoted, Battle 2nd XI and East Dean & Friston 2nd XI relegated.
Division 12 West (North): Crawley Nayee are champions, Kilnwood Vale promoted.
Division 12 West (South): Rajendra Makkunuri 80 not out off 40 balls for Goring By Sea 3rd XI.
Bosham 2nd XI are champions, Broadwater 3rd XI promoted.
Division 12 Central (North): Zac Goulds 6-6 for Haywards Heath 4th XI.
Lindfield 4th XI are champions, Scaynes Hill 3rd XI promoted.
Division 12 Central (South): Daniel Eagle 6-17 for Denton 2nd XI.
Brighton Malayalee Association are champions, St Peters 5th XI promoted.
Division 12 East (North): Crowborough 2nd XI are champions, Laughton 2nd XI promoted.
Division 12 East (South): Westfield 2nd XI are champions, Pett 2nd XI promoted.