They took just 15 overs to overhaul Kent's score of 57 all out, with Kathryn Leng following her 47 against Surrey on Tuesday with 31 not out.
The winning runs were scored by skipper Melissa Reynard and she said: "Women's cricket is strong in Yorkshire, and we're very happy to win the tournament again.
"The level of competition at these Championships increases every year, and it's a credit to our team that the youngsters who are coming into the side are able to continue the winning ways."
England skipper Clare Connor led Sussex to promotion as they made it five wins out of five in Division Two with a 184-run thrashing of Derbyshire.
Sussex piled up 290 for two in their 50 overs with New Zealand international Haidee Tiffin scoring an unbeaten 132 and then restricted their opponents to 106 for four.
Final day results
Division One
Berkshire 148-2 (Thorose 66, Guha 56no) beat Staffordshire 145 (Craven 4-22) by 8 wickets
Nottinghamshire 168-0 (Bacon 71no, Cassar 70no) bt Surrey 167 (Lowe 4-25) by 10 wickets
Yorkshire 58-0 (Leng 31no) beat Kent 57 by 10 wickets
Division Two
Lancashire 228-5 (Peters 70no) beat Cheshire 139 (White 5-29) by 89 runs
Somerset 226-5 (Collyer 94, Harper 61) beat Hertfordshire 85 (Wilkins 6-36) by 141 runs
Sussex 290-2 (Tiffen 132no, Birch 107no) beat Derbyshire 106-4 by 184 runs
Division Three
Middlesex 249-7 (Kaul 95) beat Hampshire 208-8 (Wood 74) by 49 runs