The 18-year-old prospect, who had trialled with Manchester United prior to joining Cherries, was signed on a three-and-a-half-year contract from League of Ireland outfit Longford Town in January.
O'Hanlon was loaned to Conference North club Oxford City in March where he made three starts before returning to feature in each of the development squad's pre-season matches. Subject to paperwork, he will debut in Dolphins' friendly with a Crystal Palace XI on Friday.
But Poole boss Tom Killick remains in the market for frontrunners following Ekow Elliott's shock decision to drop two levels and return to former club Blackfield & Langley.
Killick told the Daily Echo: “Josh is a player I have admired for some time. For such a young lad he has good strength and power along with a lot of technical ability.
“We knew about the possibility of this one for a while so it was nice to get it all confirmed and the timing couldn't be better with Ekow leaving.
“Like any loan, we will have to see how things pan out but if Josh performs well and finds being here beneficial, extending it is certainly something we would look to explore with Bournemouth.”
Asked whether the move would bring an end to his pursuit of new forwards, Killick added: “I don't think so, not now.
"If we hadn't lost Ekow we might have been okay but his departure created a bit of concern. I would certainly like to have another striker on board.”
On Elliott's move, Killick said: “It was purely down to money. You wouldn't drop down two divisions for football reasons but Blackfield made him an offer so lucrative that he felt he couldn't turn it down.
“It is disappointing to see a player in his mid-20s dropping down at this stage of his career but sometimes people have to make decisions for non-football reasons. It happens.”
On O'Hanlon's move, Cherries development coach Stephen Purches said: “Josh came over from Ireland having played a completely different type of football to what he has experienced here.
“From our point of view, we were always keen to get him a good number of senior games quite quickly. This will be a good experience for him and being just down the road means we can closely monitor his progress.
“We have a good relationship with Tom (Killick) after sending a lot of the boys there in the past.
"Players learn more from games than they do in training most of the time and this gives Josh the chance to do that. We hope he does well, both for himself and for Poole.”
And Purches suggested further temporary moves could be in the offing with Cherries fielding interest from clubs in League Two, the Conference Premier and the Conference South.
He added: “We got most of our lads out on loan fairly locally last year and it worked well for us so we will look to do that again. Josh is the first and he won’t be the last.
“There is a fair bit of interest in a few of the lads which is great, but we have to make sure everything is right for all parties and we will consider everything carefully before firming anything up.”