The charity is focused on assisting subsistence farmers in Africa 'regreening' degraded land to help tackle climate change.
Blinston-Jones will oversees Justdiggit's comms strategy, as well as establishing strategic partnerships with media owners and other clients. The charity's UK country director, Stuart Taylor, is a former UK CEO of Kinetic, the outdoor media planner.
Justdiggit, which was founded in the Netherlands 10 years ago, works primarily in Kenya and Tanzania but is expanding into Ethiopia and Uganda.
Blinston-Jones, who joins the charity today (22 June), said: "In the words of David Attenborough: 'Saving the planet is a communications issue.' We need to find an alternative way of communicating what needs to be done rather than the current media narrative that we are all doomed.
"What I love about Justdiggit is how they use positive storytelling to drive change amongst the communities they work with. With climate change being at the top of the agenda for governments, businesses and consumers alike, (and as cheesy as it sounds) this role is an amazing opportunity for me to be part of something that is making a real difference."
Blinston-Jones left MWWPR last year, having helped launch the US-headquartered, independent agency in London following its 2013 acquisition of Parys Communications. She became MD in 2018, when incumbent Paddy Herridge moved to UK chairman.
Blinston-Jones previously held roles at Text 100 and worked at Mantra PR for nine years until it was sold to Loewy and became Speed Communications. She later headed Speed's business communications team.