The duo both rose 10 places due to their fine performances in Melbourne, with Watson climbing to 40th and Robson three places behind.
In January they was crowned first set of two GB women being ranked inside top 50 concurrently for 26 years.
The British women reached another round in Melbourne, and both of them are up 10 places inside the latest published list.
Watson is ranked No 40 - three places prior to her compatriot, whose two beaten opponents in Australia included former Wimbledon champion Petra Kvitova.
The most notable three inside men's rankings remain unchanged, but David Ferrer moved above the injured Rafa Nadal into fourth place thanks to his semi-final appearance.
British men's primary Andy Murray continues to be world number 3.
Murray remains more than 1,000 points behind # 2 Roger Federer as the Scot must make over 3,500 points on his Melbourne conqueror Novak Djokovic if he's to attain his goal of topping the rankings.
Murray's countryman Jamie Baker continues to be rewarded for his success in qualifying to the main draw in the Australian Open by climbing 39 places to 207th, making her the clear British number two.
On Tuesday Watson continued her good form, progressing towards the second round from the Pattaya Open in Thailand.
Watson, who's going to be seeded eighth to the event, was leading the earth number 79, Timea Babos, 6-1 3-0 once the Hungarian teenager retired hurt.
Watson, 20, will now meet Latvia's Anastasija Sevastova, that is ranked 143 places below her, next round.
In the Australian Open, Watson beat Alexandra Cadantu and Ksenia Pervak before losing to fourth seed Agnieszka Radwanska, while 19-year-old Robson defeated Melanie Oudin and upset former Wimbledon champion Petra Kvitova but lost to eventual semi-finalist Sloane Stephens.
Jo Durie and Sara Gomer were a final two British women to obtain been ranked inside top 50 as well, later.
Watson broke into your top 50 first in 2012 - and Robson achieved that feat in January.
Britain's other women suffered contrasting fortunes in the latest rankings list.
Anne Keothavong slips two places to 144 while Johanna Konta moves up six place to 147.
Elena Baltacha moves down nine places to 190..