The　interaction　between　the　population　and　built　environment　is　a　constant　topic　in　urban　spaces　and　is　the　main　driving　force　of　urban　evolution.　Understanding　urban　population　distribution　and　its　relationship　with　the　built　environment　could　provide　guidance　for　urban　planning,　traffic,　and　disaster　management.　Following　this　line　of　thought,　this　study　conducted　an　empirical　analysis　in　Xi’an,　a　rapidly　developing　western　city　in　China.　Well-permeated　mobile　phone　location　data　were　used　to　represent　the　spatiotemporal　dynamics　of　the　population,　and　the　built　environment　was　characterized　from　five　perspectives—transportation,　location,　building,　greenery,　and　land　use—using　multisource　geospatial　data.　Finally,　the　dynamic　heterogeneous　influence　of　built　environment　factors　on　population　distribution　was　examined　using　multiscale　geographically　weighted　regression　(MGWR).　Overall,　the　influencing　coefficients　exhibited　a　significant　dynamic　changing　process　from　a　temporal　perspective　and　simultaneously　demonstrated　spatial　nonstationarity.　Moreover,　the　specific　findings　about　the　influence　of　each　built　environment　factor　facilitate　a　deeper　insight　into　dynamic　population　distribution　and　its　determinants.　©　2023　by　the　authors.