Both players have long since cemented their place in the squad after the internationalists' returned, with Brown adding a starting slot in Scotland A's 35-0 win over England Saxons at Netherdale.
The renewal marks the latest landmark for the pair who progressed through the national age-grade ranks together to senior professional rugby.
Edinburgh Rugby head coach, Michael Bradley, said: "It's fantastic that some of the country's top young talent is committing to the exciting future being forged at this club.
"Both Tom [Brown] and Grant [Gilchrist] have done exceptionally well this season to stake a claim for the Edinburgh Rugby jersey and exemplify the spirit and drive we look for in all the players that represent this club.
"They both have a very exciting couple of years ahead of them as they progress from being hot prospects to senior squad members and I'm delighted that those years will be spent here at Murrayfield."
Former Lornshill Academy pupil, Alloa and Stirling County lock, Gilchrist, signed for the club at the beginning of the 2010/11 season and earned the right to head to New Zealand for 18 weeks as one of three recipients of the John MacPhail scholarship, where he would hone his skills under the stewardship of All Black lock Sam Whitelock, at Canterbury Crusaders.
On his return he's slotted straight into the second-row alongside new arrival Sean Cox and has made 20 appearances so far this season, including starting spots in all of the club's Heineken Cup pool matches en route to the quarter-final.
He said: "I'm absolutely delighted with the way this season has gone for me personally.
"I improved a lot in New Zealand, both technically and as an individual, having learned from the reality check that comes with spending some extended time away from home.
"My initial targets were simply to impress the coaches with a few appearances off the bench and work my way into the team but once I started getting more exposure my expectations and ambitions changed as I pushed to start every week.
"The challenge for me now is to own that place in the second-row. It's a really exciting time at Edinburgh Rugby and all I want to do is keep playing and be involved in a winning side every week."
Brown too has made a meteoric rise to first team action.
After five replacement appearances at the tail end of last season, he has now instilled himself in the thoughts of selectors in both his preferred full-back role and on the wing.
A former pupil of Law Primary School in North Berwick and Edinburgh Academy, Tom played at all of Scotland's age-grades form U17 to U20.
He continued to chart his way through representative honours with selection for the Scotland Club International side, playing against France and Ireland in 2011, and in the Scotland Sevens squad for the London and Edinburgh legs of the HSBC Sevens World Series in the same year.
With the recent Scotland A cap to add to his international accolades, Brown feels well-placed to push on to the next level.
"I couldn't have asked for much more from my first season," said Brown.
"When you get your first contract your focus is mainly on establishing yourself in the team and getting to grips with the whole professional environment.
"Having done that and extended my contract I can now really focus on setting goals for the next two years, like cementing my place in the 15 jersey at Edinburgh and striving for selection in the senior Scotland squad in the years ahead.
"I've a really exciting couple of years ahead and I'm really forward to it."
Edinburgh Rugby new signings: WP Nel (Free State Cheetahs), Greig Tonks (Northampton Saints), Ulises Gamboa (Aironi, to the end of the season)
Edinburgh Rugby re-signings: Tom Brown, Sean Cox, Geoff Cross, David Denton, Grant Gilchrist, Gregor Hunter, Lee Jones, Greig Laidlaw, Robin Hislop, Harry Leonard, Stuart McInally, Lewis Niven, Matt Scott, Steven Turnbull, Tim Visser
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