diff --git a/cloud/parameterstore/fakeparameter/db.go b/cloud/parameterstore/fakeparameter/db.go
index 10972ace955..da921342f36 100644
--- a/cloud/parameterstore/fakeparameter/db.go
+++ b/cloud/parameterstore/fakeparameter/db.go
@@ -22,6 +22,8 @@ var (
 
 // FindOneID finds a single fake parameter by its name.
 func FindOneID(ctx context.Context, id string) (*FakeParameter, error) {
+	checkTestingEnvironment()
+
 	var p FakeParameter
 	err := evergreen.GetEnvironment().DB().Collection(Collection).FindOne(ctx, bson.M{NameKey: id}).Decode(&p)
 	if adb.ResultsNotFound(err) {
@@ -35,6 +37,8 @@ func FindOneID(ctx context.Context, id string) (*FakeParameter, error) {
 
 // FindByIDs finds one or more fake parameters by their names.
 func FindByIDs(ctx context.Context, ids ...string) ([]FakeParameter, error) {
+	checkTestingEnvironment()
+
 	if len(ids) == 0 {
 		return nil, nil
 	}
@@ -52,6 +56,8 @@ func FindByIDs(ctx context.Context, ids ...string) ([]FakeParameter, error) {
 // DeleteOneID deletes a fake parameter with the given ID. Returns whether any
 // matching parameter was deleted.
 func DeleteOneID(ctx context.Context, id string) (bool, error) {
+	checkTestingEnvironment()
+
 	res, err := evergreen.GetEnvironment().DB().Collection(Collection).DeleteOne(ctx, bson.M{NameKey: id})
 	if err != nil {
 		return false, errors.Wrap(err, "deleting fake parameter by ID")
diff --git a/cloud/parameterstore/fakeparameter/fake_parameter.go b/cloud/parameterstore/fakeparameter/fake_parameter.go
index 3738078bca8..211dedab216 100644
--- a/cloud/parameterstore/fakeparameter/fake_parameter.go
+++ b/cloud/parameterstore/fakeparameter/fake_parameter.go
@@ -18,7 +18,10 @@ import (
 // to "test".
 var ExecutionEnvironmentType = "production"
 
-func init() {
+// checkTestingEnvironment performs a safety check to verify that logic in this
+// package is only called in a testing environment. If this is called in a
+// non-testing environment, the process will exit with a fatal error.
+func checkTestingEnvironment() {
 	if ExecutionEnvironmentType != "test" {
 		grip.EmergencyFatal(message.Fields{
 			"message":     "fake Parameter Store testing code called in a non-testing environment",
@@ -41,6 +44,8 @@ type FakeParameter struct {
 
 // Insert inserts a single parameter into the fake parameter store.
 func (p *FakeParameter) Insert(ctx context.Context) error {
+	checkTestingEnvironment()
+
 	_, err := evergreen.GetEnvironment().DB().Collection(Collection).InsertOne(ctx, p)
 	return err
 }
@@ -48,6 +53,8 @@ func (p *FakeParameter) Insert(ctx context.Context) error {
 // Upsert inserts a single parameter into the fake parameter store or replaces
 // an one if one with the same ID already exists.
 func (p *FakeParameter) Upsert(ctx context.Context) error {
+	checkTestingEnvironment()
+
 	_, err := evergreen.GetEnvironment().DB().Collection(Collection).ReplaceOne(ctx, bson.M{NameKey: p.Name}, p, options.Replace().SetUpsert(true))
 	return err
 }
diff --git a/cloud/parameterstore/fakeparameter/ssm_client.go b/cloud/parameterstore/fakeparameter/ssm_client.go
index 73afb54bba0..28fb0563e4f 100644
--- a/cloud/parameterstore/fakeparameter/ssm_client.go
+++ b/cloud/parameterstore/fakeparameter/ssm_client.go
@@ -20,11 +20,14 @@ type FakeSSMClient struct{}
 // NewFakeSSMClient returns a fake SSM client implementation backed by the DB.
 // This should only be used in testing.
 func NewFakeSSMClient() *FakeSSMClient {
+	checkTestingEnvironment()
 	return &FakeSSMClient{}
 }
 
 // PutParameter inserts a parameter into the fake parameter store.
 func (c *FakeSSMClient) PutParameter(ctx context.Context, input *ssm.PutParameterInput) (*ssm.PutParameterOutput, error) {
+	checkTestingEnvironment()
+
 	name := utility.FromStringPtr(input.Name)
 	value := utility.FromStringPtr(input.Value)
 	catcher := grip.NewBasicCatcher()
@@ -55,6 +58,8 @@ func (c *FakeSSMClient) PutParameter(ctx context.Context, input *ssm.PutParamete
 // DeleteParametersSimple is the same as DeleteParameters but only returns the
 // deleted parameter names.
 func (c *FakeSSMClient) DeleteParametersSimple(ctx context.Context, input *ssm.DeleteParametersInput) ([]string, error) {
+	checkTestingEnvironment()
+
 	output, err := c.DeleteParameters(ctx, input)
 	if err != nil {
 		return nil, err
@@ -70,6 +75,8 @@ func (c *FakeSSMClient) DeleteParametersSimple(ctx context.Context, input *ssm.D
 // DeleteParameters deletes the specified parameters from the fake parameter
 // store.
 func (c *FakeSSMClient) DeleteParameters(ctx context.Context, input *ssm.DeleteParametersInput) ([]*ssm.DeleteParametersOutput, error) {
+	checkTestingEnvironment()
+
 	names := input.Names
 	if len(names) == 0 {
 		return nil, nil
@@ -98,6 +105,8 @@ func (c *FakeSSMClient) DeleteParameters(ctx context.Context, input *ssm.DeleteP
 // GetParametersSimple is the same as GetParameters but only returns the
 // parameters.
 func (c *FakeSSMClient) GetParametersSimple(ctx context.Context, input *ssm.GetParametersInput) ([]ssmTypes.Parameter, error) {
+	checkTestingEnvironment()
+
 	outputs, err := c.GetParameters(ctx, input)
 	if err != nil {
 		return nil, err
@@ -113,6 +122,8 @@ func (c *FakeSSMClient) GetParametersSimple(ctx context.Context, input *ssm.GetP
 // GetParameters retrieves the specified parameters from the fake parameter
 // store.
 func (c *FakeSSMClient) GetParameters(ctx context.Context, input *ssm.GetParametersInput) ([]*ssm.GetParametersOutput, error) {
+	checkTestingEnvironment()
+
 	names := input.Names
 	if len(names) == 0 {
 		return nil, nil
diff --git a/config.go b/config.go
index bf8b78b6e88..18df33f7135 100644
--- a/config.go
+++ b/config.go
@@ -33,7 +33,7 @@ var (
 
 	// ClientVersion is the commandline version string used to control updating
 	// the CLI. The format is the calendar date (YYYY-MM-DD).
-	ClientVersion = "2025-01-09a"
+	ClientVersion = "2025-01-09b"
 
 	// Agent version to control agent rollover. The format is the calendar date
 	// (YYYY-MM-DD).
diff --git a/model/github_app_auth.go b/model/github_app_auth.go
index 25a51ef90dd..16486705e37 100644
--- a/model/github_app_auth.go
+++ b/model/github_app_auth.go
@@ -26,7 +26,7 @@ func githubAppCheckAndRunParameterStoreOp(ctx context.Context, appAuth *githubap
 	if err != nil {
 		return errors.Wrapf(err, "checking project ref '%s' to verify if GitHub app should use Parameter Store", appAuth.Id)
 	}
-	isPSEnabled, err := isParameterStoreEnabledForProject(ctx, ref)
+	isPSEnabled, err := isParameterStoreEnabledForProject(ctx, ref, true)
 	if err != nil {
 		return errors.Wrapf(err, "checking if Parameter Store is enabled for project '%s'", appAuth.Id)
 	}
diff --git a/model/project_vars.go b/model/project_vars.go
index 21dcdb3b0dc..3a180383ddd 100644
--- a/model/project_vars.go
+++ b/model/project_vars.go
@@ -610,10 +610,11 @@ func getUpdatedParamMappings(original ParameterMappings, upserted, deleted map[s
 }
 
 // isParameterStoreEnabledForProject checks if Parameter Store is enabled for a
-// project.
+// project. If ignoreProjectFeatureFlag is enabled, the project will use
+// Parameter Store regardless of the project-level feature flag.
 // TODO (DEVPROD-11882): remove feature flag checks once all project vars are
 // using Parameter Store and the rollout is stable.
-func isParameterStoreEnabledForProject(ctx context.Context, ref *ProjectRef) (bool, error) {
+func isParameterStoreEnabledForProject(ctx context.Context, ref *ProjectRef, ignoreProjectFeatureFlag bool) (bool, error) {
 	flags, err := evergreen.GetServiceFlags(ctx)
 	if err != nil {
 		return false, errors.Wrap(err, "getting service flags")
@@ -622,6 +623,10 @@ func isParameterStoreEnabledForProject(ctx context.Context, ref *ProjectRef) (bo
 		return false, nil
 	}
 
+	if ignoreProjectFeatureFlag {
+		return true, nil
+	}
+
 	if ref == nil {
 		return false, errors.Errorf("ref is nil")
 	}
@@ -901,7 +906,7 @@ func (projectVars *ProjectVars) checkAndRunParameterStoreOp(ctx context.Context,
 		"project_id": projectVars.Id,
 		"epic":       "DEVPROD-5552",
 	}))
-	isPSEnabled, err := isParameterStoreEnabledForProject(ctx, ref)
+	isPSEnabled, err := isParameterStoreEnabledForProject(ctx, ref, false)
 	grip.Error(message.WrapError(err, message.Fields{
 		"message":    "could not check if Parameter Store is enabled for project; assuming it's disabled and will not use Parameter Store",
 		"op":         opName,
diff --git a/operations/flags.go b/operations/flags.go
index 60f342c766d..c3fb03d64f9 100644
--- a/operations/flags.go
+++ b/operations/flags.go
@@ -44,6 +44,7 @@ const (
 	syncTasksFlagName         = "sync_tasks"
 	syncTimeoutFlagName       = "sync_timeout"
 	tasksFlagName             = "tasks"
+	testingEnvFlagName        = "testing-env"
 	traceEndpointFlagName     = "trace_endpoint"
 	uncommittedChangesFlag    = "uncommitted"
 	variantsFlagName          = "variants"
@@ -89,7 +90,12 @@ func serviceConfigFlags(flags ...cli.Flag) []cli.Flag {
 		cli.BoolFlag{
 			Name:  overwriteConfFlagName,
 			Usage: "overwrite the configuration in the DB with the file",
-		})
+		},
+		cli.BoolFlag{
+			Name:  testingEnvFlagName,
+			Usage: "if true, run Evergreen service as a testing environment",
+		},
+	)
 }
 
 func addProjectFlag(flags ...cli.Flag) []cli.Flag {
diff --git a/operations/service_deploy_smoke.go b/operations/service_deploy_smoke.go
index c0235f6087e..f0d3baa166c 100644
--- a/operations/service_deploy_smoke.go
+++ b/operations/service_deploy_smoke.go
@@ -41,7 +41,7 @@ func startLocalEvergreen() cli.Command {
 				return errors.Wrap(err, "getting working directory")
 			}
 			binary := filepath.Join(wd, "clients", runtime.GOOS+"_"+runtime.GOARCH, "evergreen")
-			if err := smokeRunBinary(exit, "web.service", wd, binary, "service", "web", "--db", "evergreen_local"); err != nil {
+			if err := smokeRunBinary(exit, "web.service", wd, binary, "service", "web", "--db", "evergreen_local", "--testing-env"); err != nil {
 				return errors.Wrap(err, "running web service")
 			}
 			<-exit
diff --git a/operations/service_web.go b/operations/service_web.go
index 1b2910cda00..c6c67ae2c9e 100644
--- a/operations/service_web.go
+++ b/operations/service_web.go
@@ -11,6 +11,8 @@ import (
 
 	"github.com/evergreen-ci/evergreen"
 	"github.com/evergreen-ci/evergreen/auth"
+	"github.com/evergreen-ci/evergreen/cloud/parameterstore"
+	"github.com/evergreen-ci/evergreen/cloud/parameterstore/fakeparameter"
 	"github.com/evergreen-ci/evergreen/service"
 	"github.com/evergreen-ci/gimlet"
 	"github.com/evergreen-ci/utility"
@@ -74,6 +76,27 @@ func startWebService() cli.Command {
 			db := parseDB(c)
 			env, err := evergreen.NewEnvironment(ctx, confPath, versionID, clientS3Bucket, db, tp)
 			grip.EmergencyFatal(errors.Wrap(err, "configuring application environment"))
+
+			if c.Bool(testingEnvFlagName) {
+				// If running in a testing environment (e.g. local Evergreen),
+				// use a fake implementation of Parameter Store since testing
+				// environments won't have access to a real Parameter Store
+				// instance.
+				fakeparameter.ExecutionEnvironmentType = "test"
+
+				opts := parameterstore.ParameterManagerOptions{
+					PathPrefix:     env.Settings().ParameterStore.Prefix,
+					CachingEnabled: true,
+					SSMClient:      fakeparameter.NewFakeSSMClient(),
+					DB:             env.DB(),
+				}
+				pm, err := parameterstore.NewParameterManager(ctx, opts)
+				if err != nil {
+					return errors.Wrap(err, "creating parameter manager")
+				}
+				env.SetParameterManager(pm)
+			}
+
 			evergreen.SetEnvironment(env)
 			if c.Bool(overwriteConfFlagName) {
 				grip.EmergencyFatal(errors.Wrap(env.SaveConfig(ctx), "saving config"))