Surrey were in a solid position against Essex when they reached 42 for one after the sixth over.
However, the hosts collapsed to 123 all out, with Matt Critchley standout for Essex, taking 3‑16 off four overs, while only Josh Philippe reached 33 runs.
Michael Pepper top‑scored with an unbeaten 71, guiding Essex to a comfortable run chase completed in just 17 overs.
Surrey’s defeat left them second behind Hampshire, ending their hopes of hosting a quarter‑final.
Hilton Cartwright and Ben Mayes built a crucial 112‑run stand in ten overs to rescue already qualified Hampshire’s chase, securing a four‑wickets win over Sussex.
Batting to 187, Cartwright struck 70 runs from only 31 deliveries and Mayes remained unbeaten on 55 as the Hawks, after being 61 for five, clinched the victory off the penultimate delivery.
Dan Hughes contributed 55 and Charlie Tear remained 40 not out for Sussex, but it proved insufficient as the Hove side finished bottom of the group with just three wins from twelve fixtures.
Hampshire’s triumph ensured they would host a quarter‑final match.
Middlesex ended a disappointing campaign on a positive note with a 14‑run win in a dead‑rubber clash against the Kent Spitfires at Canterbury.
Zafar Gohar took 3‑38, dismissing Zak Crawley for 10, as the Spitfires fell short of their target after Ben Geddes top‑scored with 32 in Middlesex’s total of 172 for six.
