The Deans left it late but Harry Jackson's 90th-minute strike ensured Michael Birmingham' s made came away with all three points.
It made it consecutive league victories for Horndean, who have won two and drawn the other of their opening three Wessex League Premier Division fixtures so far.
In fact, Birmingham's men are also the only defence to remain unblemished of the 41 sides across the two Wessex League divisions.
And the Horndean boss believes his squad are getting the rewards for the work they've been putting in over recent weeks.
Birmingham said: ‘I said to the lads at half time it might take them until the 89th-minute to get the winner, but they had to keep plugging, keep probing and do it the way we want to do it. Grinding out a 1-0 win away from home is just as good as winning 7-0 at home.
‘They’re getting the rewards because they’ve gone back to basics and they’re working extremely hard.’
Horndean did concede four goals in a 4-2 FA Cup defeat at AFC Portchester earlier this month, yet they're still to concede in 270 minutes of league football this term.
Ben Anderson struck a post, Sam Hookey saw an effort cannon off the crossbar while striker Zak Willett had an attempt cleared off the line as the Deans could count themselves slightly unfortunate not to go in leading at the break.
It looked as though Horndean would have to settle for a point prior to Jackson striking late on to wrap up the victory.
And, on the balance of chances created, Birmingham felt his troops just edged proceedings - although he conceded it was far from a vintage display.
He added: ‘Bashley started off the better, they came at us, we looked a little bit unsure of ourselves, it was really weird after the victory we had last week.
‘I thought if you had a look at the game in general, I thought a draw would have been a fair result, but if you have a look at the clear-cut chances, we hit the post, the crossbar and we had two other good chances.
‘Second half we huffed and puffed again, both teams did, the defences were on top because of the lack of quality from both sides in the final third.
‘We were fortunate enough that we still looked fit and sharp in the 90th-minute, we went and hunted them, forced them into an error and came away with the late goal from Harry Jackson.’